OFFSET
1,1
COMMENTS
a(n) is the sum of all parts plus the total number of parts of all partitions of n into equal parts. - Omar E. Pol, Nov 30 2019
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
FORMULA
G.f.: Sum_{k>=1} (k + 1) * x^k/(1 - x^k)^2. - Ilya Gutkovskiy, Aug 14 2019
EXAMPLE
For n = 4 the partitions of 4 into equal parts are [4], [2,2], [1,1,1,1]. The sum of all parts is 4 + 2 + 2 + 1 + 1 + 1 + 1 = 12. There are 7 parts, so a(4) = 12 + 7 = 19. - Omar E. Pol, Nov 30 2019
MATHEMATICA
Array[Total[{#, 1} DivisorSigma[{0, 1}, #]] &, 48] (* Michael De Vlieger, Dec 01 2019 *)
PROG
(PARI) a(n) = n*numdiv(n) + sigma(n) \\ Michel Marcus, Jun 02 2013
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Ctibor O. Zizka, Nov 29 2008
STATUS
approved