OFFSET
0,5
COMMENTS
Exponential transform of A000587 (complementary Bell numbers).
FORMULA
MATHEMATICA
nmax = 27; CoefficientList[Series[Exp[Exp[1 - Exp[x]] - 1], {x, 0, nmax}], x] Range[0, nmax]!
Table[Sum[(-1)^k StirlingS2[n, k] BellB[k], {k, 0, n}], {n, 0, 27}]
a[n_] := a[n] = Sum[Binomial[n - 1, k - 1] BellB[k, -1] a[n - k], {k, 1, n}]; a[0] = 1; Table[a[n], {n, 0, 27}]
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Jun 03 2019
STATUS
approved