A360899 G.f. satisfies A(x) = 1 + x/(1 + x^4) * A(x/(1 + x^4)).
1, 1, 1, 1, 1, 0, -2, -5, -9, -13, -10, 10, 60, 155, 281, 325, 5, -1214, -4094, -8786, -12571, -5642, 35339, 149264, 363838, 596714, 417156, -1373639, -7048541, -18932245, -34095357, -29271979, 68706873, 413250742, 1193425228, 2293494882, 2201716631
Offset: 0
Keywords
Programs
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PARI
a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=0, (i-1)\4, (-1)^j*binomial(i-1-3*j, j)*v[i-4*j])); v;
Formula
a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/4)} (-1)^k * binomial(n-1-3*k,k) * a(n-1-4*k).