A367655 - OEIS

%I #9 Nov 26 2023 08:38:13

%S 1,2,5,14,39,111,314,894,2539,7224,20536,58413,166102,472410,1343448,

%T 3820748,10865805,30901790,87882171,249931270,710786078,2021427153,

%U 5748794540,16349171957,46495891170,132231060820,376055838670,1069476434880,3041515866674

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

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

%o (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;

%Y Cf. A367656, A367657, A367658.

%Y Cf. A127680.

%K nonn

%O 0,2

%A _Seiichi Manyama_, Nov 26 2023