OFFSET
1,3
FORMULA
a(n) +(-n-2)*a(n-1) +(2*n-1)*a(n-2) +(-n+2)*a(n-3)=0. - R. J. Mathar, Jul 28 2013
a(n) = exp(1)*n*Gamma(n,1) - 2*Gamma(n+1,0). - Martin Clever Mar 27 2023
EXAMPLE
a(4) = 4*(a(3)+1) = 4*4 = 16.
MATHEMATICA
A224869[1] := -1; A224869[n_] := A224869[n - 1]n + n; Table[A224869[n], {n, 40}] (* Alonso del Arte, Jul 22 2013 *)
PROG
(Python)
a=-1
for n in range(2, 24):
print str(a)+', ',
a= n*(a+1)
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Alex Ratushnyak, Jul 22 2013
STATUS
approved