OFFSET
1,2
LINKS
David A. Corneth, Table of n, a(n) for n = 1..10000 (first 1000 terms from Amiram Eldar)
EXAMPLE
If k = 10, then sigma(10,10) = 1 + 1024 + 9765625 + 10000000000 = 1009766650 is divisible by k = 10.
MATHEMATICA
Do[s=DivisorSigma[n, n]; If[IntegerQ[s/n], Print[n]], {n, 1, 10000}]
Select[Range[6500], Divisible[DivisorSigma[#, #], #]&] (* Harvey P. Dale, Feb 06 2019 *)
PROG
(PARI) isok(k) = !(sigma(k, k) % k); \\ Michel Marcus, Aug 10 2020
(PARI) is(n) = {my(d = divisors(n), v = vecsum(vector(#d - 1, i, Mod(d[i], n)^n))); lift(v)==0} \\ David A. Corneth, Aug 10 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Jan 14 2002
STATUS
approved