OFFSET
1,3
FORMULA
Conjecture: a(n) ~ Bell(n). - Vaclav Kotesovec, May 12 2022
MATHEMATICA
A[m_, n_] := A[m, n] = Which[m == 1, BellB[n], m > n >= 1, 0, True, A[m - 1, n] - A[m - 1, m - 1] A[m - 1, n - m + 1]]; a[n_] := A[n, n]; a /@ Range[1, 26]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, May 12 2022
STATUS
approved