121680

Appears in sequences

• a(n) = (2*n+1)^2*n!.at n=6A007681
• Coordination sequence for E_8 lattice.at n=3A008340
• Cube of the lower triangular normalized 2nd kind Stirling matrix.at n=20A027496
• First diagonal of A027496.at n=5A027501
• Triangle inverse to that in A046899.at n=51A046900
• a(n) = n*(n+1)*(n+2)*(n^2+7*n+32)/120.at n=24A051747
• Expansion of e.g.f. 1/(1-2*x-x^2).at n=6A052555
• Initial values for f(x)=phi(sigma(x)) such that iteration of f ends in cycle of length=11.at n=17A096888
• Triangle read by rows: T(n,k) = n!*Pell(n-k+1)/k!, where Pell(n)=A000129(n).at n=21A110327
• Molecular topological indices of the complete graph K_n.at n=39A181617
• Numbers with prime factorization pq^2r^2s^4.at n=18A190319