OFFSET
1,2
FORMULA
a(p) = 2*p, p prime.
EXAMPLE
a(6) = 34; a(6) = Sum_{p|6, p prime} Sum_{d|6} lcm(d,p) = Sum_{p|6, p prime} (lcm(1,p) + lcm(2,p) + lcm(3,p) + lcm(6,p)) = (lcm(1,2) + lcm(2,2) + lcm(3,2) + lcm(6,2)) + (lcm(1,3) + lcm(2,3) + lcm(3,3) + lcm(6,3)) = (2+2+6+6) + (3+6+3+6) = 34.
PROG
(PARI) a(n) = my(f=factor(n), d=divisors(f)); sum(k=1, #f~, sum(j=1, #d, lcm(d[j], f[k, 1]))); \\ Michel Marcus, Feb 19 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Feb 18 2022
STATUS
approved