A091754 Fifth column (m=6) of array A091752 ((-1,2)Stirling2).

1, 80, 9520, 1786400, 493292800, 189065676800, 96179539456000, 62739188255744000, 51070871935283200000, 50753775178192486400000, 60478693661116393062400000, 85121458839683971088384000000, 139713174879733993267265536000000, 264509913735543445488643604480000000

Offset: 3

Author

Wolfdieter Lang, Feb 27 2004

Keywords

• nonn
• easy
• changed

Crossrefs

Cf. A052502, A091752.

Programs

Mathematica

a[n_] := ((3*(n-2))!/((3^(n-2))*(n-2)!))*(9*n^2-27*n+12)/4!; Array[a, 20, 3] (* Amiram Eldar, Sep 01 2025 *)

Formula

a(n) = A091752(n, 6), n>=3.

a(n) = ((3*(n-2))!/((3^(n-2))*(n-2)!))*(9*n^2-27*n+12)/4! = A052502(n-2)*(9*n^2-27*n+12)/4!, n>=3.

a(n) ~ (3/e)^(2*n-5/2) * n^(2*n-2) / 8. - Amiram Eldar, Sep 01 2025