A377633 E.g.f. satisfies A(x) = (1 + x * A(x)^2 * exp(x*A(x)^2))^2.
1, 2, 22, 474, 15512, 685450, 38251212, 2582466950, 204744089104, 18650699228754, 1919767092675860, 220378941471652942, 27916112634179586456, 3868191824049865945178, 582034397153512353488284, 94509039130326185624148150, 16472375319790734221438146592, 3067435511995844132675459958178
Offset: 0
Keywords
Programs
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PARI
a(n) = n!*sum(k=0, n, k^(n-k)*binomial(4*n+2, k)/(n-k)!)/(2*n+1);
Formula
E.g.f.: B(x)^2, where B(x) is the e.g.f. of A364989.
a(n) = (n!/(2*n+1)) * Sum_{k=0..n} k^(n-k) * binomial(4*n+2,k)/(n-k)!.