OFFSET
1,2
COMMENTS
Chowla's function (A048050) = sum of divisors of n except 1 and n.
Sequence contains all primes; see A070037 for nonprime terms. - Charles R Greathouse IV, Apr 14 2010
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
chowla[1] = 0; chowla[n_] := DivisorSigma[1, n] - n - 1; Select[Range[270], Divisible[chowla[#], EulerPhi[#]] &] (* Amiram Eldar, Dec 01 2019 *)
PROG
(PARI) j=[]; for(n=1, 600, if(Mod(sigma(n)-n-1, eulerphi(n)) == 0, j=concat(j, n))); j
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason Earls, Jul 24 2001
STATUS
approved