login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A332508 a(n) = Sum_{d|n} binomial(n+d-2, n-1). 7
1, 3, 7, 25, 71, 280, 925, 3561, 12916, 49346, 184757, 710255, 2704157, 10427747, 40119781, 155288897, 601080391, 2334714319, 9075135301, 35352181116, 137846759282, 538302226628, 2104098963721, 8233718962365, 32247603703576, 126412458920775, 495918551104687 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = [x^n] Sum_{k>=1} x^k / (1 - x^k)^n.

MATHEMATICA

Table[DivisorSum[n, Binomial[n + # - 2, n - 1] &], {n, 1, 27}]

Table[SeriesCoefficient[Sum[x^k/(1 - x^k)^n, {k, 1, n}], {x, 0, n}], {n, 1, 27}]

PROG

(PARI) a(n) = sumdiv(n, d, binomial(n+d-2, n-1)); \\ Michel Marcus, Feb 14 2020

CROSSREFS

Cf. A000005, A000203, A007437, A059358, A073570, A101289, A308814, A332470.

Sequence in context: A148722 A148723 A148724 * A309911 A148725 A148726

Adjacent sequences:  A332505 A332506 A332507 * A332509 A332510 A332511

KEYWORD

nonn

AUTHOR

Ilya Gutkovskiy, Feb 14 2020

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 24 07:33 EDT 2021. Contains 345416 sequences. (Running on oeis4.)