A371779 a(n) = Sum_{k=0..floor(n/3)} binomial(4*n+2,n-3*k).

1, 6, 45, 365, 3078, 26565, 232831, 2063235, 18435021, 165780758, 1498533273, 13603087800, 123920995101, 1132284232215, 10372554403620, 95233251146671, 876081280823430, 8073359613286509, 74513645742072841, 688682977876117698, 6373025238727622277

Offset

0,2

Links

Table of n, a(n) for n=0..20.

Formula

a(n) = [x^n] 1/(((1-x)^3-x^3) * (1-x)^(3*n)).

Prog

(PARI) a(n) = sum(k=0, n\3, binomial(4*n+2, n-3*k));

Crossrefs

Cf. A371777, A371778, A371780.

Cf. A066381.

Sequence in context: A095003 A004988 A257633 * A007193 A153399 A007194

Adjacent sequences: A371776 A371777 A371778 * A371780 A371781 A371782

Keyword

nonn

Author

Seiichi Manyama, Apr 05 2024

Status

approved