645120

Appears in sequences

• Double factorial of even numbers: (2n)!! = 2^n*n!.at n=7A000165
• Sorted list of orders of Weyl groups of types A_n, B_n, D_n, E_n, F_4, G_2.at n=22A001217
• Double factorials n!!: a(n) = n*a(n-2) for n > 1, a(0) = a(1) = 1.at n=14A006882
• Expansion of tanh(log(1+1/x)).at n=8A009769
• Denominator of [x^(2n+1)] in the Taylor expansion arcsinh(cosec(x) - cot(x)).at n=3A013523
• Theta series of laminated lattice LAMBDA_20.at n=3A023942
• Number of subgroups L of Z^n with the property that for every a in Z^n there exists precisely one b in L with d(a,b) <= 1. Here d denotes Euclidean distance.at n=8A026739
• Number of solutions to non-attacking rooks problem on n X n board that are invariant under 180-degree rotation.at n=14A037223
• Number of solutions to non-attacking rooks problem on n X n board that are invariant under 180-degree rotation.at n=15A037223
• Number of degree-n irreducible polynomials over GF(2) with trace = 0 and subtrace = 1.at n=25A042979
• Number of degree-n irreducible polynomials over GF(2) with trace = 0 and subtrace = 0.at n=25A042980
• Number of degree-n irreducible polynomials over GF(2) with trace = 1 and subtrace = 0.at n=25A042981
• Value of phi in arithmetic progression of at least 5 terms having the same value of phi in A050515.at n=17A050517
• Denominators of coefficients in the formal power series a(x) such that a(a(x)) = exp(x) - 1.at n=7A052105
• E.g.f. (1+x^2-2x^3)/(1-2x).at n=7A052576
• a(n) = 2*n*n!.at n=8A052582
• E.g.f. (1-x)^2/(1-2x+x^2-x^3).at n=8A052625
• E.g.f. (2-2x-x^2)/((1-2x)(1-x^2)).at n=7A052647
• E.g.f. x^4/(1-2x).at n=8A052652
• Expansion of e.g.f. x^3*(1-x)/(1-2*x).at n=8A052671