A369425 Expansion of Sum_{n>=1} x^(n*(n+1)/2)*((1+x)/(1-x))^n.

1, 2, 3, 6, 10, 15, 24, 40, 64, 97, 144, 216, 328, 496, 737, 1074, 1546, 2218, 3186, 4578, 6555, 9318, 13130, 18358, 25530, 35398, 49002, 67735, 93416, 128392, 175704, 239352, 324680, 438888, 591672, 795993, 1068984, 1433032, 1917128, 2558648, 3405784, 4520872, 5984872, 7903256, 10413561

Offset

1,2

Links

Table of n, a(n) for n=1..45.

Prog

(PARI) my(N=66, x='x+O('x^N)); Vec(sum(n=1, N, x^(n*(n+1)/2)*((1+x)/(1-x))^n))

Crossrefs

Cf. A369424.

Sequence in context: A320597 A227566 A280421 * A018141 A178659 A268064

Adjacent sequences: A369422 A369423 A369424 * A369426 A369427 A369428

Keyword

nonn,easy

Author

Joerg Arndt, Jan 23 2024

Status

approved