A385287 a(0) = 1, a(1) = 0; a(n) = a(n-2) + Sum_{k=0..n-1} k * a(k) * a(n-1-k).
1, 0, 1, 2, 7, 32, 177, 1148, 8535, 71552, 668037, 6877742, 77448741, 947342072, 12512378625, 177525399952, 2693306735145, 43516930747192, 746123462304725, 13531269497675506, 258807528403312427, 5206929233591435496, 109929366336996502793, 2430108139669253103756
Offset: 0
Keywords
Programs
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PARI
a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=2, n, v[i+1]=v[i-1]+sum(j=0, i-1, j*v[j+1]*v[i-j])); v;
Formula
G.f. A(x) satisfies A(x) = 1/( 1 - x^2 - x^2 * (d/dx A(x)) ).