OFFSET
1,2
EXAMPLE
a(15) = Sum_{p|15} nextprime(p) = nextprime(3) + nextprime(5) = 5 + 7 = 12.
MATHEMATICA
Table[Sum[NextPrime[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