OFFSET
1,3
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}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Jul 25 2018
STATUS
approved