A372012 G.f. A(x) satisfies A(x) = 1/( 1 + x*(1 - 4*x*A(x))^(1/2) ).
1, -1, 3, -5, 17, -31, 119, -211, 937, -1483, 8015, -10187, 73369, -62193, 713907, -234857, 7358657, 1881661, 80117735, 69295469, 917837521, 1334044075, 11006114883, 21830065899, 137275956089, 333858963899, 1769128762419, 4940496514271, 23409778504937
Offset: 0
Keywords
Programs
-
PARI
a(n) = (-1)^n*sum(k=0, n, 4^(n-k)*binomial(n, k)*binomial(k/2, n-k)/(n-k+1));
Formula
a(n) = (-1)^n * Sum_{k=0..n} 4^(n-k) * binomial(n,k) * binomial(k/2,n-k)/(n-k+1).