A372107 G.f. A(x) satisfies A(x) = 1/( 1 - 4*x/(1 - x*A(x)) )^(1/2).
1, 2, 8, 38, 198, 1094, 6296, 37338, 226596, 1400518, 8785524, 55793170, 358000418, 2317478554, 15116570956, 99259594982, 655580568854, 4352370307750, 29028865425828, 194416887461778, 1306961109488350, 8815875534728018, 59650171332148564
Offset: 0
Keywords
Crossrefs
Cf. A372088.
Programs
-
PARI
a(n) = sum(k=0, n, 4^k*binomial(n/2+k/2-1/2, k)*binomial(n-1, n-k)/(n-k+1));
Formula
a(n) = Sum_{k=0..n} 4^k * binomial(n/2+k/2-1/2,k) * binomial(n-1,n-k)/(n-k+1).