Sequences

a(n) is the solution to the postage stamp problem with 5 denominations and n stamps.

a(n) is the solution to the postage stamp problem with 6 denominations and n stamps.

a(n) = solution to the postage stamp problem with n denominations and 2 stamps.

a(n) is the solution to the postage stamp problem with n denominations and 3 stamps.

a(n) is the solution to the postage stamp problem with n denominations and 4 stamps.

a(n) is the solution to the postage stamp problem with n denominations and 5 stamps.

a(n) = solution to the postage stamp problem with n denominations and 6 stamps.

Sorted list of orders of Weyl groups of types A_n, B_n, D_n, E_n, F_4, G_2.

a(n) = 3^n mod 100.

Triangular numbers of form a(a+1)(a+2).

Wieferich primes: primes p such that p^2 divides 2^(p-1) - 1.

Number of distinct primes dividing n (also called omega(n)).

Number of prime divisors of n counted with multiplicity (also called big omega of n, bigomega(n) or Omega(n)).

Prime gaps: differences between consecutive primes.

If F(n) is the n-th Fibonacci number, then a(2n) = (F(2n+1) + F(n+2))/2 and a(2n+1) = (F(2n+2) + F(n+1))/2.

Number of consistent arcs in a tournament with n nodes.

Lerch's function q_2(n) = (2^{phi(t)} - 1)/t where t = 2*n - 1.

Number of odd divisors of n.

Orders of sporadic simple groups.

Numbers k such that phi(sigma(k)) = k.

Number of undirected closed knight's tours on a 2n X 2n chessboard.

Number of nonisomorphic projective planes of order n.

Numbers k such that 9*k = (k written backwards), k > 0.

Unsigned Stirling numbers of first kind s(n,6).

Unsigned Stirling numbers of the first kind s(n,7).

Taxi-cab numbers: sums of 2 cubes in more than 1 way.

Differences of reciprocals of unity.

Differences of reciprocals of unity.

Differences of reciprocals of unity.

Numbers that are the sum of 3 nonnegative cubes in more than 1 way.

Expansion of 1/((1-2x)(1-3x)(1-6x)).

Differences of reciprocals of unity.

Differences of reciprocals of unity.

Eulerian numbers (Euler's triangle: column k=7 of A008292, column k=6 of A173018).

Eulerian numbers (Euler's triangle: column k=8 of A008292, column k=7 of A173018).

Numbers that are the sum of 4 cubes in more than 1 way.

Squares of Catalan numbers.

Squares of Bell numbers.

Squares of primes.

Squares of tetrahedral numbers: a(n) = binomial(n+3,n)^2.

Number of alternating permutations of order n.

Number of permutations of order n with the length of longest run equal to 3.

Number of permutations of order n with the length of longest run equal to 4.

Number of permutations of order n with the length of longest run equal to 5.

Squares of Lucas numbers.

Squares of partition numbers.

Squares of numbers of trees.

Squares of numbers of rooted trees.

Number of labeled n-node trees with unlabeled end-points.

A sequence of sorted odd primes 3 = p_1 < p_2 < ... < p_m such that p_i-2 divides the product p_1*p_2*...*p_(i-1) of the earlier primes and each prime factor of p_i-1 is a prime factor of twice the product.