OFFSET
1,2
FORMULA
From Wesley Ivan Hurt, May 10 2024: (Start)
a(p^k) = p^(k-1) * prime(p^(k-1)) for primes p and k >= 1.
MATHEMATICA
Table[n*DivisorSum[n, Prime[n/#]/# &, PrimeQ[#] &], {n, 60}]
PROG
(PARI) a(n) = my(vp=primes([1, n])); n*sum(i=1, #vp, if (!(n % vp[i]), prime(n/vp[i])/vp[i])); \\ Michel Marcus, May 11 2024
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, Feb 03 2024
STATUS
approved