Result details
Numbers & representations
How it works
A sequence is an ordered collection indexed by an integer. Fibonacci uses F(0)=0 and F(1)=1; each later term is the sum of the previous two.
What you can do
Generate integer progressions, squares, cubes, powers, factorials, Pascal rows, look-and-say and Thue–Morse terms. Custom recurrence uses two seeds and x[n+2] = A × x[n+1] + B × x[n].
How to use it
- Choose a sequence, count and starting index. Set seeds, coefficients or step when shown. Arithmetic uses a + n × step; geometric uses a × ratioⁿ. Choose a text separator.
- Calculate, inspect the result details, then copy or download TXT. Ctrl/⌘ + Enter also calculates. Editing clears old results; Undo restores input and settings.
Errors and limits
1–500 terms; indices −2000…2000. Negative indices are accepted only for Fibonacci, Lucas and polynomial or arithmetic modes. Pascal starts at row 0 and allows 50 rows. Look-and-say starts with 1 at index 0 and ends by index 24; factorial ends at 1000. Seeds and coefficients are integers within ±10¹².
Word seeds: Fibonacci W₀=0,W₁=01; Tribonacci W₀=0,W₁=01,W₂=0102. Concatenate the preceding two/three words from newest to oldest; maximum indices 20/15. Gijswijt starts at 1 and appends the largest repeated-suffix exponent, ending at index 299. Kolakoski starts 1,2,2; paperfolding 1,1,0,1; Rudin–Shapiro outputs ±1. Fibonacci/Lucas prime subsequences contain distinct prime values ≤10¹²; start is their subsequence index.
Limits: 100,000 input characters per box, 100 digits per numeric token, 200 input values and 200,000 output characters. Fraction numerators and denominators and sequence terms are limited to 5000 digits. Scientific notation is not accepted.
Calculations run in a separate browser worker. Cancel stops the job; the 8-second time limit also covers worker loading. Try a smaller batch after a timeout.
Frequently asked questions
Does the starting index mean a starting value?
It selects the position n, not a minimum output value. With Fibonacci, start 10 and count 1 returns 55. Integers use the index itself; even and odd modes return 2n and 2n+1. Large integers are written in full.
Are my numbers uploaded?
No. File reading and calculation happen in this browser. Input is not stored in the URL or sent to a calculation service. Text files must be UTF-8.