1321205760

Appears in sequences

• One eighth of octo-factorial numbers.at n=6A034976
• a(0) = 1; for n > 0, a(n) = n!*4^n/2.at n=8A051711
• Number of invertible n X n matrices mod 4 (i.e., over the ring Z_4).at n=4A065128
• A labeled structure simultaneously a tree and a cycle.at n=7A066319
• Smallest k-almost prime between twin primes (for k >= 2).at n=24A068525
• Least m with n*(n+1)/2 divisors.at n=22A081620
• Let A(n) be the matrix in the group GL(n,2) such that for 1 <= i, j <= n: A[i,j] = 1 if i+j = n+1 A[i,j] = 0 if i+j != n+1. a(n) is the size of the centralizer of A(n) in GL(n,2).at n=7A087540
• a(n) = 2^n * (n + 3)!!.at n=11A155160
• A sequence related to the period T of a simple gravity pendulum for arbitrary amplitudes.at n=4A223068
• a(n) gives the determinant of a bisymmetric n X n matrix involving the entries 1, 2, ..., A002620(n+1).at n=12A259056
• Denominators in expansion of W(exp(x)) about x=1, where W is the Lambert function.at n=8A274448
• Number of invertible 4 X 4 matrices mod n.at n=3A305186
• a(n) is the number of numbers whose largest prime power factor equals A000961(n).at n=37A305215
• Number of (undirected) Hamiltonian paths in the 2n-crossed prism graph.at n=18A308136
• Array read by antidiagonals: T(n,k) is the order of the group GL(n,Z_k).at n=32A316622
• a(n) = pos(M(n)), where M(n) is the n X n matrix with every term = 4, and pos(M(n)) is the positive part of the determinant of M(n); see A380661.at n=7A381724