OFFSET
1,2
EXAMPLE
2 is in this sequence because 2 divides A001157(2) - 1 = 5 - 1 = 4.
MATHEMATICA
Select[Range@ 180, Function[n, Total@ Boole@ Map[Divisible[ DivisorSigma[2, n] - #, n] &, Divisors@ n] > 0]] (* Michael De Vlieger, Mar 19 2017 *)
PROG
(Magma) [[n: k in [1..n] | Denominator(n/k) eq 1 and
Denominator(((DivisorSigma(2, n))-k)/n) eq 1]: n in [1..100]];
(PARI) isok(n) = fordiv(n, d, if (!((sigma(n, 2) - d) % n), return (1))); \\ Michel Marcus, Mar 18 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Mar 18 2017
STATUS
approved