Sequences

Number of ways n married couples can sit in a row without any spouses next to each other.

The Ehrenfeucht-Mycielski sequence (1,2-version): a maximally unpredictable sequence.

Let P(n) of a sequence s(1),s(2),s(3),... be obtained by leaving s(1),...,s(n) fixed and reversing every n consecutive terms thereafter; apply P(2) to 1,2,3,... to get PS(2), then apply P(3) to PS(2) to get PS(3), then apply P(4) to PS(3), etc. This sequence is the limit of PS(n).

Main diagonal of Kimberling's expulsion array (A035486).

Numbers not of form "nearest integer to n*tau", tau = (1+sqrt(5))/2.

Number of M-sequences from multicomplexes on at most 5 variables with no monomial of degree greater than n.

a(n) = 1 + ceiling((n-1)*phi^2), phi = (1+sqrt(5))/2.

Nearest integer to n*tau where tau = (1+sqrt(5))/2.

a(n) = a(n-1) + (3+(-1)^n)*a(n-2)/2.

First column of spectral array W(sqrt 2).

a(n) = 4*a(n-1) - 2*a(n-2) with a(0) = 1, a(1) = 4.

First row of 2-shuffle of spectral array W( sqrt 2 ).

First column of array associated with monotonic justified array.

First column of array associated with lexicographically justified array.

First column of array associated with reverse lexicographically justified array.

Number of irreducible positions of size n in Montreal solitaire.

Number of irreducible positions of size n in Montreal solitaire.

Optimal cost of search tree for searching an ordered array of n elements with cost k of probing element k.

Optimal cost of search tree.

Number of labeled regular tournaments with 2n+1 nodes.

Number of labeled Eulerian digraphs with n nodes.

Number of labeled Eulerian oriented graphs with n nodes.

Number of Eulerian circuits on the complete graph K_{2n+1}, divided by (n-1)!^(2n+1).

Number of unlabeled trivalent 3-connected bipartite planar graphs with 2n nodes.

Number of unlabeled trivalent 3-connected bipartite planar graphs with 2n nodes without subgraphs R2 and R4.

Number of unlabeled trivalent 3-connected bipartite planar graphs with 2n nodes without subgraphs R1 and R4.

Next term is uniquely the sum of 3 earlier terms.

Next term is uniquely the sum of 3 earlier terms.

The binary numbers (or binary words, or binary vectors, or binary expansion of n): numbers written in base 2.

Numbers in base 3.

Numbers in base 4.

Numbers in base 5.

Numbers in base 6.

Numbers in base 7.

Numbers in base 8.

Numbers in base 9.

Expansion of theta_3 / theta_4.

Primeth recurrence: a(n+1) = a(n)-th prime.

Number of unlabeled bisectable trees with 2n+1 nodes.

Number of labeled trivalent (or cubic) 2-connected graphs with 2n nodes.

Number of labeled trivalent (or cubic) 3-connected graphs with 2n nodes.

Number of labeled trivalent (or cubic) cyclically 4-connected graphs with 2n nodes.

Number of labeled disconnected trivalent (or cubic) graphs with 2n nodes.

Erroneous version of A006903.

Number of elements (a b, c d) in GL(2,Z) with det = -1, trace n and 0 <= a <= {b, c} <= d.

Number of labeled Eulerian 3-regular digraphs with n nodes.

Number of labeled odd degree trees with 2n nodes.

Number of labeled 2-regular digraphs with n nodes.

Number of connected labeled 2-regular digraphs with n nodes.

Number of labeled 2-regular oriented graphs with n nodes.