81749606400
domain: N
Appears in sequences
- Double factorial of even numbers: (2n)!! = 2^n*n!.at n=11A000165
- Double factorials n!!: a(n) = n*a(n-2) for n > 1, a(0) = a(1) = 1.at n=22A006882
- Denominator of [x^(2n+1)] in the Taylor expansion sin(cosec(x)-cot(x))= x/2 + x^3/48 - x^5/1280 - 55*x^7/129024 - 143*x^9/1769472 + ...at n=5A013517
- Denominator of [x^(2n+1)] in the Taylor expansion arcsinh(cosec(x) - cot(x)).at n=5A013523
- Number of solutions to non-attacking rooks problem on n X n board that are invariant under 180-degree rotation.at n=22A037223
- Number of solutions to non-attacking rooks problem on n X n board that are invariant under 180-degree rotation.at n=23A037223
- E.g.f. (1+x^2-2x^3)/(1-2x).at n=11A052576
- E.g.f. (2-2x-x^2)/((1-2x)(1-x^2)).at n=11A052647
- Expansion of e.g.f. (1 + x^3 - 2*x^4)/(1-2*x).at n=11A052694
- Denominators of series related to triangular cacti.at n=11A058928
- a(n) = 2^(2n+1)*(2n+1)!.at n=5A067626
- Maximal order of a finite subgroup of the group GL(n,Q).at n=10A085495
- Terms of A110142 at positions p(n)+1, where p(n) = A000041(n) is the number of partitions of n; a(n) = A110142(p(n)+1) for n>=1, with a(0) = 1.at n=21A110144
- a(n) = n!! mod !n.at n=20A216443
- a(n) = n!! mod n!at n=22A216466
- Union of the factorial numbers (A000142) and the double factorials numbers (A006882).at n=32A268645
- Irregular triangle T(n,m), denominators of coefficients in a power/Fourier series expansion of the plane pendulum's exact time dependence.at n=25A274131
- Largest automorphism group size for a binary self-dual code of length 2n.at n=10A322309
- a(n) = Product_{k=0..n} Nimsum (2*k + 2), with Nimsum (2 + 2) = 0 replaced by 1.at n=11A352526
- Number of Wachs permutations of size n.at n=22A359039