OFFSET
1,1
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..500
FORMULA
EXAMPLE
m=95, phi(95)=72, sigma(95)=120, product=8640, product/(m+1)=90.
MATHEMATICA
Do[s=EulerPhi[n]*DivisorSigma[1, n]; If[IntegerQ[s/(n+1)]&&!PrimeQ[n], Print[n]], {n, 1, 100000}]
Select[Range[14000], !PrimeQ[#]&&Divisible[EulerPhi[#]DivisorSigma[1, #], #+1]&] (* Harvey P. Dale, Jul 08 2017 *)
PROG
(PARI) { n=0; for (m=1, 10^9, s=eulerphi(m)*sigma(m); if (s%(m+1) == 0 && !isprime(m), write("b065148.txt", n++, " ", m); if (n==500, return)) ) } \\ Harry J. Smith, Oct 12 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Oct 18 2001
EXTENSIONS
Offset changed from 0 to 1 by Harry J. Smith, Oct 12 2009
Definition clarified by Harvey P. Dale, Jul 08 2017
STATUS
approved