OFFSET
1,3
FORMULA
a(1) = 1; a(n) = Sum_{k=1..n-1} (-1)^k * Stirling2(n-1,k) * a(k).
MATHEMATICA
terms = 25; A[_] = 0; Do[A[x_] = Normal[Integrate[1 + A[1 - Exp[x] + O[x]^(terms + 1)], x] + O[x]^(terms + 1)], terms]; CoefficientList[A[x], x] Range[0, terms]! // Rest
a[1] = 1; a[n_] := a[n] = Sum[(-1)^k StirlingS2[n - 1, k] a[k], {k, 1, n - 1}]; Table[a[n], {n, 1, 25}]
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Jul 03 2020
STATUS
approved