OFFSET
1,2
COMMENTS
a(37) > 10^13. - Giovanni Resta, Jun 12 2013
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..36 (terms < 10^13)
MAPLE
with(numtheory): A055681:=n->`if`(sigma(n)-phi(n) mod n=0, n, NULL): seq(A055681(n), n=1..10^5); # Wesley Ivan Hurt, Sep 13 2014
MATHEMATICA
Do[If[Mod[DivisorSigma[1, n]-EulerPhi[n], n]==0, Print[n]], {n, 1, 10^9}]
PROG
(PARI)
for(n=1, 10^8, if((sigma(n)-eulerphi(n))%n==0, print1(n, ", "))) \\ Derek Orr, Sep 13 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jun 09 2000
EXTENSIONS
a(16)-a(26) from Donovan Johnson, Feb 28 2012
STATUS
approved