A227791 Central terms of the triangle in A227550.

1, 2, 8, 36, 176, 940, 5568, 37128, 280992, 2410812, 23250080, 249164344, 2934303264, 37617633976, 521009920256, 7748175156240, 123095897716800, 2080205257723740, 37253560076385120, 704703668205036120, 14039778681732928800, 293831851498842784680

Offset: 0

Author

Reinhard Zumkeller, Aug 05 2013

Keywords

• nonn

Crossrefs

Cf. A074911, A225621, A227550.

Programs

Haskell

a227791 n = a227550 (2 * n) n

Maple

b:= proc(x, y) option remember; `if`(x=0, y!,
      b(x-1, y)+b(sort([x, y-1])[]))
    end:
a:= n-> b(n$2):
seq(a(n), n=0..26);  # Alois P. Heinz, Jul 14 2021

Mathematica

T[n_, 0] := n!; T[n_, n_] := n!;
T[n_, k_] /; 0Jean-François Alcover, Nov 03 2022 *)

Formula

a(n) = A074911(2*n,n).