A383529 a(n) = Sum_{k=0..floor(n/4)} binomial(n+k,k) * binomial(n-3*k,k).

1, 1, 1, 1, 6, 13, 22, 33, 91, 226, 474, 877, 1938, 4586, 10326, 21409, 45867, 103423, 234271, 511426, 1110544, 2460822, 5526188, 12282861, 27073156, 59942598, 133861825, 298874122, 664509858, 1476912298, 3294571470, 7362783137, 16437438777, 36665641447, 81881083752, 183115618015

Offset

0,5

Comments

Diagonal of the rational function 1 / ((1-x)*(1-y) - y^4).

Links

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

Prog

(PARI) a(n) = sum(k=0, n\4, binomial(n+k, k)*binomial(n-3*k, k));

Crossrefs

Cf. A001850, A383528.

Sequence in context: A072212 A028872 A049718 * A394802 A036707 A054311

Adjacent sequences: A383526 A383527 A383528 * A383530 A383531 A383532

Keyword

nonn

Author

Seiichi Manyama, Apr 29 2025

Status

approved