OFFSET
1,2
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..100
EXAMPLE
Sigma(10) = 18 = 2*3^2, usigma(18) = (2+1)*(9+1) = 30, divisible by 10, so 10 is in the sequence.
Sigma(24) = 60 = 2^2*3*5, usigma(60) = 5*4*6 = 120, divisible by 24, so 24 is in the sequence.
MATHEMATICA
q[n_] := Divisible[Times @@ (1 + Power @@@ FactorInteger[DivisorSigma[1, n]]), n]; Select[Range[200000], q] (* Amiram Eldar, Aug 26 2022 *)
PROG
(PARI) for(n=1, 10^9, s=sigma(n); om=omega(s); f=factorint(s); pr=1; for(j=1, om, pr=pr*(f[j, 1]^f[j, 2]+1)); if(pr%n==0, print(n))) \\ Donovan Johnson, Mar 12 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Corrected and extended by Jud McCranie, Oct 28 2001
Missing first term added and offset corrected by Donovan Johnson, Mar 12 2013
STATUS
approved