OFFSET
1,2
COMMENTS
If p is prime, a(p) = Sum_{p|p} p * nextprime(p/p) = 2*p.
EXAMPLE
a(12) = Sum_{p|12} p * nextprime(12/p) = 2*7 + 3*5 = 14 + 15 = 29.
MATHEMATICA
Table[Sum[k*NextPrime[n/k] (PrimePi[k] - PrimePi[k - 1]) (1 - Ceiling[n/k] + Floor[n/k]), {k, n}], {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Jun 12 2021
STATUS
approved