OFFSET
0,2
FORMULA
a(n) = Sum_{k=0..n} (2*(n-k))!/((n-k)!*(n-k)!)*2^((n-k)*(n+k-3)/2).
PROG
(PARI) a(n)=sum(k=0, n, (2*(n-k))!/((n-k)!*(n-k)!)*2^((n-k)*(n+k-3)/2))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Mar 14 2006
STATUS
approved