A366975 Expansion of Sum_{k >=1} x^(3*k)/(1-x^k)^(k+1).

0, 0, 1, 2, 3, 5, 5, 9, 8, 14, 9, 25, 11, 27, 24, 40, 15, 65, 17, 75, 55, 65, 21, 176, 44, 90, 110, 182, 27, 324, 29, 270, 197, 152, 195, 695, 35, 189, 324, 847, 39, 925, 41, 759, 1016, 275, 45, 2215, 377, 1182, 730, 1365, 51, 2338, 1418, 3072, 1025, 434, 57, 7536, 59

Offset

1,4

Links

Table of n, a(n) for n=1..61.

Formula

a(n) = Sum_{d|n} binomial(d+n/d-3,d) for n > 1.

If p is prime, a(p) = p - 2.

Prog

(PARI) a(n) = if(n<2, 0, sumdiv(n, d, binomial(d+n/d-3, d)));

Crossrefs

Cf. A081543, A366974.

Cf. A318636.

Sequence in context: A096736 A128188 A318636 * A267582 A360072 A139127

Adjacent sequences: A366972 A366973 A366974 * A366976 A366977 A366978

Keyword

nonn

Author

Seiichi Manyama, Oct 30 2023

Status

approved