A367655 - OEIS

A367655

G.f. A(x) satisfies A(x) = 1 / (1 - x - x * (1 + x) * A(x^2)).

1, 2, 5, 14, 39, 111, 314, 894, 2539, 7224, 20536, 58413, 166102, 472410, 1343448, 3820748, 10865805, 30901790, 87882171, 249931270, 710786078, 2021427153, 5748794540, 16349171957, 46495891170, 132231060820, 376055838670, 1069476434880, 3041515866674

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..28.

FORMULA

a(0) = 1; a(n) = a(n-1) + Sum_{k=0..n-1} a(floor(k/2)) * a(n-1-k).

PROG

(PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=v[i]+sum(j=0, i-1, v[j\2+1]*v[i-j])); v;

CROSSREFS

Cf. A367656, A367657, A367658.

Cf. A127680.