OFFSET
1,4
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Rafael Jakimczuk, Arithmetical Functions over the Powerful Part of an Integer, ResearchGate, 2024.
MATHEMATICA
a[n_] := Denominator[Times @@ (1 + 1/Select[FactorInteger[n], Last[#] > 1 &][[;; , 1]])]; Array[a, 100]
PROG
(PARI) a(n) = {my(f = factor(n)); denominator(prod(i = 1, #f~, if(f[i, 2] == 1, 1, 1 + 1/f[i, 1]))); }
CROSSREFS
KEYWORD
nonn,easy,frac
AUTHOR
Amiram Eldar, Mar 02 2024
STATUS
approved