A367714 - OEIS

%I #9 Nov 28 2023 08:50:45

%S 1,2,4,8,17,36,76,162,345,734,1564,3332,7097,15121,32216,68634,146228,

%T 311544,663748,1414136,3012859,6418971,13675802,29136686,62076510,

%U 132255753,281774605,600328670,1279017082,2724981797,5805650101,12369100408,26352715431

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

%F a(n) = 1 + Sum_{k=0..n-1} a(floor(k/3)) * 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\3+1]*v[i-j])); v;

%Y Cf. A367713, A367715.

%Y Cf. A367656, A367691.

%K nonn

%O 0,2

%A _Seiichi Manyama_, Nov 28 2023