OFFSET
1,2
COMMENTS
If p is prime, a(p) = Sum_{p|p} lcm(p,p/p) = p.
EXAMPLE
a(12) = Sum_{p|12} lcm(p,12/p) = lcm(2,6) + lcm(3,4) = 6 + 12 = 18.
MATHEMATICA
Table[Sum[LCM[k, 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 13 2021
STATUS
approved