A381600 G.f. A(x) satisfies A(x) = 1/(1 - x * A(x)^2 * A(x*A(x)^2)^2).
1, 1, 5, 39, 383, 4360, 55201, 758877, 11157081, 173623407, 2838995592, 48515016273, 862904739711, 15923514065053, 304089551295359, 5997295071211547, 121944040723497105, 2552667957311169834, 54944459391676448365, 1214747696691087352576, 27559533140410855702244
Offset: 0
Keywords
Programs
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PARI
a(n, k=1) = if(k==0, 0^n, k*sum(j=0, n, binomial(2*n+j+k, j)/(2*n+j+k)*a(n-j, 2*j)));
Formula
See A381592.