OFFSET
0,2
FORMULA
a(2*n+1) = 2^n*n!, a(2*n+2) = 3*2^n*n! for n>0, with a(0) = 1.
PROG
(PARI) a(n)=if(n==0, 1, if(n%2==1, 2^(n\2+1)*(n\2+1)!, 3*2^((n-1)\2)*((n-1)\2)!))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 14 2005
STATUS
approved