OFFSET
2,5
COMMENTS
If n is the product of k distinct primes, then a(n) = sigma(k).
Records occur at n = 2, 6, 30, 210, 30030, ... . - R. J. Mathar, Jun 18 2014
If n = p^k where p is prime and k is a positive integer, a(p^k) = sigma(omega(p^k)) = sigma(1) = 1. - Wesley Ivan Hurt, May 21 2021
LINKS
G. C. Greubel, Table of n, a(n) for n = 2..5000
MAPLE
with(numtheory):
A243915 := proc(n)
sigma(nops(factorset(n))) ;
end proc:
seq(A243915(n), n=2..100); # R. J. Mathar, Jun 18 2014
MATHEMATICA
Table[DivisorSigma[1, PrimeNu[n]], {n, 2, 100}]
PROG
(PARI) for(n=2, 50, print1(sigma(omega(n)), ", ")) \\ G. C. Greubel, May 17 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, Jun 14 2014
STATUS
approved