Last modified March 12 06:42 EDT 2026. Contains 393715 sequences.

May 4, 2025 · Important: The main OEIS lookup page is https://oeis.org. Use that page for looking up a sequence, searching the database, contributing new sequences, editing sequences, etc.

Successive rows give the Fibonacci numbers A000045, the Lucas numbers A000204, the doubled Fibonacci numbers A013588, the trebled Fibonacci numbers A022086, A022087, A000285, …

Feb 3, 2025 · It is like a dictionary or fingerprint file for number sequences. Also worth visiting are the pages dealing with Puzzle sequences, Classic sequences and Hot sequences. You might also like to …

F (n) is the number of possible binary sequences of length n that obey the sequential construction rule: if last symbol is 0, add the complement (1); else add 0 or 1.

The On-Line Encyclopedia of Integer Sequences (or OEIS) is a huge collection of number sequences, maintained by The OEIS Foundation. Many of these sequences have spectacular illustrations, some …

El-Sedy & Siksek prove that this sequence contains arbitrarily long subsequences of consecutive terms; that is, the upper uniform density of this sequence is 1.

Every sequence in the OEIS has an A-number, such as A001850. If you know the A-number you can retrieve the sequence directly by typing it (with the A) into the search page.

A number n is prime if and only if it is different from zero and different from a unit and each multiple of n decomposes into factors such that n divides at least one of the factors.

The number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 773", based on the 5-celled von Neumann neighborhood.