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A371680
G.f. satisfies A(x) = ( 1 + x * A(x)^2 * (1 + A(x)) )^2.
0
1, 4, 44, 648, 10960, 200992, 3886928, 78043488, 1611405504, 33998715264, 729793915264, 15886841223936, 349900041893376, 7782694227059712, 174573007616191744, 3944500600180286976, 89696369377912622080, 2051147782339517224960
OFFSET
0,2
FORMULA
G.f.: B(x)^2 where B(x) is the g.f. of A363380.
a(n) = Sum_{k=0..n} binomial(n,k) * binomial(4*n+2*k+2,n)/(2*n+k+1).
PROG
(PARI) a(n, r=2, t=4, u=2) = r*sum(k=0, n, binomial(n, k)*binomial(t*n+u*k+r, n)/(t*n+u*k+r));
CROSSREFS
Sequence in context: A053315 A005721 A103870 * A056063 A218224 A177749
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 02 2024
STATUS
approved