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A371655
G.f. satisfies A(x) = 1 + x * A(x) * (1 + A(x))^2.
2
1, 4, 32, 336, 4032, 52352, 716032, 10161408, 148229120, 2208921600, 33482670080, 514630230016, 8001860567040, 125640146354176, 1989285578473472, 31725578742464512, 509178657425326080, 8217766225008656384, 133287551280741351424, 2171450128344786403328
OFFSET
0,2
LINKS
FORMULA
a(n) = (1/n) * Sum_{k=0..floor((n-1)/2)} 4^(n-k) * binomial(n,k) * binomial(2*n-k,n-1-2*k) for n > 0.
PROG
(PARI) a(n) = if(n==0, 1, sum(k=0, (n-1)\2, 4^(n-k)*binomial(n, k)*binomial(2*n-k, n-1-2*k))/n);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 01 2024
STATUS
approved