A367715 - OEIS

%I #7 Nov 28 2023 08:50:49

%S 1,2,4,8,16,33,68,140,288,594,1225,2526,5208,10740,22148,45673,94184,

%T 194224,400524,825950,1703249,3512395,7243168,14936668,30801992,

%U 63519044,130987274,270118452,557031032,1148694482,2368807011,4884890405,10073490200

%N G.f. A(x) satisfies A(x) = 1 / ((1 - x) * (1 - x * (1 + x + x^2 + x^3) * A(x^4))).

%F a(n) = 1 + Sum_{k=0..n-1} a(floor(k/4)) * a(n-1-k).

%o (PARI) a_vector(n) = my(v=vector(n+1)); for(i=0, n, v[i+1]=1+sum(j=0, i-1, v[j\4+1]*v[i-j])); v;

%Y Cf. A367713, A367714.

%Y Cf. A367657, A367692.

%K nonn

%O 0,2

%A _Seiichi Manyama_, Nov 28 2023