I often have to generate a geometric sequence so I created this simple online utility that does it for me. It lets you generate however many geometric series numbers you need in any base. It works in the browser and is powered by alien technology from the future.

## Geometric Progression Generator Options

Start and Common Ratio
Count and Separator
Base

## Geometric Progression Generator Examples (click to try!)

Geometric Series of Cubes
In this example, we start the geometric series from 1 and calculate 50 of its members. The common ratio for this series is set to 3, which means that each subsequent value in the series is tripled and we get a list of cubes.
`1, 3, 9, 27, 81, 243, 729, 2187, 6561, 19683, 59049, 177147, 531441, 1594323, 4782969, 14348907, 43046721, 129140163, 387420489, 1162261467, 3486784401, 10460353203, 31381059609, 94143178827, 282429536481, 847288609443, 2541865828329, 7625597484987, 22876792454961, 68630377364883, 205891132094649, 617673396283947, 1853020188851841, 5559060566555523, 16677181699666569, 50031545098999707, 150094635296999121, 450283905890997363, 1350851717672992089, 4052555153018976267, 12157665459056928801, 36472996377170786403, 109418989131512359209, 328256967394537077627, 984770902183611232881, 2954312706550833698643, 8862938119652501095929, 26588814358957503287787, 79766443076872509863361, 239299329230617529590083`
Series starting value.
How many values to generate?
Series common ratio value.
Separate terms with this value.
Decimal Base
Rational Common Ratio
In this example, we use a fractional common ratio of -0.2 for the geometric progression. As the ratio is negative and less than one, we get an alternating (changing sign from minus to plus) and decaying geometric progression.
```-1
0.2
-0.04
0.008
-0.0016
0.00032
-0.000064
0.0000128
-0.00000256
0.000000512```
Series starting value.
How many values to generate?
Series common ratio value.
Separate terms with this value.
Decimal Base
Hex Geometric Sequence
In this example, we generate a fun geometric sequence in hexadecimal base. We start from 10 (which is "a" in the base 16) and compute the first 20 sequence terms. As the ratio is set to -1, the absolute value of the terms remains unchanged, however the sign changes every time.
`a; -a; a; -a; a; -a; a; -a; a; -a; a; -a; a; -a; a; -a; a; -a; a; -a`
Series starting value.
How many values to generate?
Series common ratio value.
Separate terms with this value.
This geometric series generator works entirely in your browser and is written in JavaScript. To get the job done, it uses a single `array` and a `for` loop. First, it initializes `array` with the `start`ing value, which is specified in the options. Then, it creates a `for` loop with the condition to stop when `array` reaches `count` (series length; specified in options) members. In the loop, it keeps track of `array`'s last element, multiplies it by the `ratio` (common ratio; specified in options), and adds the new term at the end of `array` by using the `array.push()` function. To work with large numbers, it uses the `bignumber.js` library and all multiplication operations are performed by bignumber's `times()` function. When the loop ends, it `array.map()`s bignumber's `toString(base)` function to convert series terms into `base` (specified in options). After this, it `array.join()`s all terms with the `separator` value (sequence value separator; also specified in the options).