A367718 G.f. A(x) satisfies A(x) = 1 / ((1 + x) * (1 - x * (1 + x + x^2 + x^3) * A(x^4))).

1, 0, 2, 2, 6, 9, 20, 36, 72, 138, 269, 520, 1010, 1958, 3798, 7365, 14284, 27704, 53728, 104202, 202089, 391939, 760128, 1474208, 2859096, 5544986, 10754022, 20856528, 40449464, 78448346, 152143931, 295070345, 572264028, 1109857872, 2152475724, 4174545216

Offset

0,3

Links

Table of n, a(n) for n=0..35.

Formula

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

Prog

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

Crossrefs

Cf. A005043, A367716, A367717.

Cf. A367694, A367715.

Sequence in context: A359896 A339426 A000021 * A000022 A034805 A192659

Adjacent sequences: A367715 A367716 A367717 * A367719 A367720 A367721

Keyword

nonn

Author

Seiichi Manyama, Nov 28 2023

Status

approved