OFFSET
0,2
FORMULA
a(n) ~ n! * (1 + 3*exp(1)/2 - exp(-1)/2). - Vaclav Kotesovec, Jun 05 2021
EXAMPLE
a(0) = 1;
a(1) = (a(0)+1)*1 = (1+1)*1 = 2 ;
a(2) = a(1)*2+2 = (2*2)+2 = 6 ;
a(3) = (a(2)+3)*3 = (6+3)*3 = 9 ;
MAPLE
a:= proc(n) a(n):= n*a(n-1) + n^(1+(n mod 2)) end: a(0):= 1:
seq(a(n), n=0..22); # Alois P. Heinz, May 21 2021
MATHEMATICA
a[0] = 1; a[n_] := a[n] = n*(a[n - 1] + If[OddQ[n], n, 1]); Array[a, 30, 0] (* Amiram Eldar, May 21 2021 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Amrit Awasthi, May 21 2021
STATUS
approved