A317275 a(1) = 1; a(n) = Sum_{k=1..n-1} |Stirling1(n-1,k)|*a(k)*a(n-k).

1, 1, 2, 9, 97, 3105, 409318, 301069244, 1523141657289, 61447697339843710, 22299766257043761657829, 80922067241038150103930448880, 3230152742688615187688660954252643194, 1547248455508510864175770056662224501358437847

Offset: 1

Author

Ilya Gutkovskiy, Jul 25 2018

Keywords

• nonn

Crossrefs

Cf. A008275, A137731, A143805.

Programs

Mathematica

a[n_] := a[n] = Sum[Abs[StirlingS1[n - 1, k]] a[k] a[n - k], {k, n - 1}]; a[1] = 1; Table[a[n], {n, 14}]