OFFSET
0,3
FORMULA
a(n) = Sum_{k=1..n} (-1)^(n - k) * |Stirling1(k+1,2)|.
MATHEMATICA
Table[Sum[(-1)^(n - k) HarmonicNumber[k] k!, {k, 1, n}], {n, 0, 22}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Nov 27 2019
STATUS
approved