A369904 - OEIS

A369904

a(n) = n * Sum_{p|n, p prime} sigma(n/p) / p.

0, 1, 1, 6, 1, 18, 1, 28, 12, 36, 1, 100, 1, 62, 42, 120, 1, 189, 1, 208, 68, 138, 1, 456, 30, 188, 117, 364, 1, 612, 1, 496, 144, 312, 86, 1038, 1, 386, 194, 960, 1, 1080, 1, 820, 477, 558, 1, 1936, 56, 955, 318, 1120, 1, 1782, 162, 1688, 392, 876, 1, 3336, 1, 998, 789

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,4

LINKS

Table of n, a(n) for n=1..63.

FORMULA

a(p^k) = p^(k-1)*(p^k-1)/(p-1), for prime p and k >= 1. - Wesley Ivan Hurt, Jun 26 2024

MATHEMATICA

Table[n*DivisorSum[n, DivisorSigma[1, n/#]/# &, PrimeQ[#] &], {n, 100}]

CROSSREFS

Cf. A000203 (sigma), A323599, A329354, A369740, A369903.

Sequence in context: A049325 A250646 A277068 * A373573 A092371 A187552

Adjacent sequences: A369901 A369902 A369903 * A369905 A369906 A369907

KEYWORD

nonn,easy

AUTHOR

Wesley Ivan Hurt, Feb 05 2024

STATUS

approved