OFFSET
1,2
COMMENTS
If p is prime, a(p) = Sum_{d|p} d^sopf(d) = 1^0 + p^p = p^p + 1.
EXAMPLE
a(6) = Sum_{d|6} d^sopf(d) = 1^0 + 2^2 + 3^3 + 6^5 = 7808.
MATHEMATICA
Table[Sum[i^Sum[k (PrimePi[k] - PrimePi[k - 1]) (1 - Ceiling[i/k] + Floor[i/k]), {k, i}] (1 - Ceiling[n/i] + Floor[n/i]), {i, n}], {n, 30}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, May 23 2021
STATUS
approved