I often have to generate the look and say sequence so I created this simple online utility that does it for me. It lets you calculate however many look and say series terms you need, starting from any initial state. It works in the browser and is powered by alien technology from the future.

Look And Say Sequence Generator Options

Initial State
Start and Count
Separator

Look And Say Sequence Generator Examples (click to try!)

Regular Look and Say Sequence
In this example, we calculate the first fifteen integers of the say what you see sequence, printing each term on a new line.
1
11
21
1211
111221
312211
13112221
1113213211
31131211131221
13211311123113112211
11131221133112132113212221
3113112221232112111312211312113211
1321132132111213122112311311222113111221131221
11131221131211131231121113112221121321132132211331222113112211
311311222113111231131112132112311321322112111312211312111322212311322113212221
Initial value to construct the look and say sequence from.
Starting position for the sequence.
How many values to generate?
Separate sequence terms with this value.
Sequence from Letters
In this example, we generate the look and say series from the "abc" initial value. We describe what we see and say: "one a, one b, one c", and write the following term down: "1a1b1c". The digits in each next value increase or change, but the three initial letters remain unchanged.
abc
1a1b1c
111a111b111c
311a311b311c
13211a13211b13211c
111312211a111312211b111312211c
Initial value to construct the look and say sequence from.
Starting position for the sequence.
How many values to generate?
Separate sequence terms with this value.
Constant Sequence
This example demonstrates the only case of the look and say sequence when the terms remain unchanged. We start the series with the "22" value and describe it as "two twos", thus, getting the same next term "22".
22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22
Initial value to construct the look and say sequence from.
Starting position for the sequence.
How many values to generate?
Separate sequence terms with this value.
One-sided Series
In this example, we start the sequence from a single letter "k". We generate 5 items and separate them with the arrow symbol. If you look closely, you can see that the digits appear only on the left side and "k" always remains on the right side! The same scenario will happen for every single letter symbol (including digits). If k=3, then this sequence is called the Conway sequence.
k → 1k → 111k → 311k → 13211k
Initial value to construct the look and say sequence from.
Starting position for the sequence.
How many values to generate?
Separate sequence terms with this value.
Sequence from Brackets
This example forms the sequence from a pair of square brackets. In each successive sequence value, the numbers appear only between and in front of the brackets. These numbers are the same, moreover, they form two regular look and say sequences (that you see in example one).
[]
1[1]
111[111]
311[311]
13211[13211]
111312211[111312211]
31131122211[31131122211]
1321132132211[1321132132211]
Initial value to construct the look and say sequence from.
Starting position for the sequence.
How many values to generate?
Separate sequence terms with this value.
Series without Spaces
In this example, we generate 16 terms of the LaS sequence starting from the 3rd position and concatenate all of them together by setting the separator option to the empty string.
21121111122131221113112221111321321131131211131221132113111231131122111113122113311213211321222131131122212321121113122113121132111321132132111213122112311311222113111221131221111312211312111312311211131122211213211321322113312221131122113113112221131112311311121321123113213221121113122113121113222123113221132122211321132132211331121321133112111312211213211312111322211231131122211311123113321112132113222113121132111113122113121113222123211211131221232112311311222112111312211311123113322112132113213221133112132123123112111312211332211311122113122131131122211311123113321112131221123113112211121312211213211321322112311311222113311213212322211211131221131211132221232112111312111213111213211231131122212322211331222113112211
Initial value to construct the look and say sequence from.
Starting position for the sequence.
How many values to generate?
Separate sequence terms with this value.

How Does This Look And Say Sequence Generator Work?

This look and say series generator works entirely in your browser and is written in JavaScript. As each subsequent member of the series is formed by reading off the digits of the previous member, it uses the nextElement() function to calculate every next member. In the first iteration, it passes the initial-state value (specified in options) to this function, gets the return value, and in all next iterations, it passes the return value from the previous call. This function uses only three variables – symbol, counter, and result, and a single for loop over the current element. The variable symbol is the character it's currently looking at, counter is how many times it has seen this symbol repeated, and result is used for building the return value. In the loop, it compares the current symbol with the next one. If they are the same, then it increments the counter value; otherwise, it appends counter + symbol to the result. When this loop finishes, it returns the result and it gets appended to the lookAndSaySeq array. This algorithm continues as long as lookAndSaySeq.length is less than count (sequence length; specified in options). When the algorithm terminates, this utility displays the lookAndSaySeq array. If you entered a custom term separator in the options, then it calls the lookAndSaySeq.join(separator) function that converts the array with look and say values to a string, separating all the values with the specified character.

Created by Browserling

This look and say sequence generator was created by me and my team at Browserling. Behind the scenes, it's actually powered by Browserling's programmer tools that are used by millions of people every month. Browserling itself is an online cross-browser testing service powered by alien technology. Check it out!

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