OFFSET
1,2
FORMULA
a(1) = 0, a(n) = a(n-1)*n + (1 + (-1)^n)*(n-1)!. - Daniel Suteu, Feb 06 2017
MATHEMATICA
Table[ n! HarmonicNumber[ Floor[ n/2]], {n, 20}] (* Robert G. Wilson v, Dec 11 2004 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Ralf Stephan, Dec 10 2004
STATUS
approved