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A116913 Inverse Moebius transform of pentagonal numbers. 3
1, 6, 13, 28, 36, 69, 71, 120, 130, 186, 177, 301, 248, 363, 378, 496, 426, 663, 533, 798, 734, 897, 783, 1245, 961, 1254, 1210, 1547, 1248, 1914, 1427, 2016, 1806, 2148, 1926, 2821, 2036, 2685, 2522, 3270, 2502, 3702, 2753, 3801, 3510, 3939, 3291, 5053, 3648 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = Sum_{d|n} d*(3*d-1)/2.

G.f.: Sum_{k>=1} k*(3*k-1)/2*x^k/(1 - x^k). - Ilya Gutkovskiy, May 23 2017

MATHEMATICA

Table[Sum[d*(3d - 1)/2, {d, Divisors[n]}], {n, 101}] (* Indranil Ghosh, May 23 2017 *)

PROG

(PARI) a(n) = sumdiv(n, d, d*(3*d-1)/2); \\ Michel Marcus, Mar 25 2015

CROSSREFS

Cf. A000326 (pentagonal numbers).

Inverse Moebius transforms of polygonal numbers: A007437 (k=3), A001157 (k=4), this sequence (k=5), A278945 (k=6), A278947 (k=7).

Sequence in context: A301687 A173559 A086224 * A016071 A086652 A159694

Adjacent sequences:  A116910 A116911 A116912 * A116914 A116915 A116916

KEYWORD

easy,nonn

AUTHOR

Jonathan Vos Post, Mar 19 2006

EXTENSIONS

More terms from Michel Marcus, Mar 25 2015

STATUS

approved

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Last modified August 1 22:36 EDT 2021. Contains 346408 sequences. (Running on oeis4.)