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URL: https://oeis.org/A371523

⇱ A371523 - OEIS

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A371523
G.f. A(x) satisfies A(x) = (1 + x*A(x)^3 / (1-x))^2.
7
1, 2, 15, 142, 1533, 17924, 220936, 2827218, 37202580, 500228562, 6842899886, 94931338876, 1332438761910, 18887047322030, 269986427261981, 3887654399820062, 56337997080499605, 821021578186212094, 12024687038651388155, 176900548019426869808, 2612917215947948178941
OFFSET
0,2
FORMULA
a(n) = 2 * Sum_{k=0..n} binomial(n-1,n-k) * binomial(6*k+1,k)/(5*k+2).
G.f.: A(x) = B(x)^2 where B(x) is the g.f. of A349333.
PROG
(PARI) a(n) = 2*sum(k=0, n, binomial(n-1, n-k)*binomial(6*k+1, k)/(5*k+2));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 26 2024
STATUS
approved