OFFSET
1,2
FORMULA
a(p^k) = p^(k*(1-p^k)/(1-p)), for prime p and k >= 1. - Wesley Ivan Hurt, Jun 26 2024
MATHEMATICA
Table[DivisorSum[n, n^DivisorSigma[1, n/#] &, PrimeQ[#] &], {n, 30}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, Feb 05 2024
STATUS
approved