OFFSET
1,1
FORMULA
G.f.: Sum_{k>=1} prime(k+1) * x^k / (1 - x^k).
a(n) = Sum_{d|n} prime(d+1).
MATHEMATICA
nmax = 60; CoefficientList[Series[Sum[Prime[k + 1] x^k/(1 - x^k), {k, 1, nmax}], {x, 0, nmax}], x] // Rest
Table[DivisorSum[n, Prime[# + 1] &], {n, 1, 60}]
PROG
(PARI) a(n) =sumdiv(n, d, prime(d+1)); \\ Michel Marcus, Apr 22 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Apr 22 2022
STATUS
approved