OFFSET
1,1
EXAMPLE
Aliquot parts of 21 are 1, 3, 7 and 22/(1+3+7) = 22/11 = 2.
MAPLE
with(numtheory): P:=proc(n) if not isprime(n) and frac((n+1)/(sigma(n)-n))=0 then n; fi; end: seq(P(i), i=2..100000);
MATHEMATICA
Select[Range[10^6], CompositeQ[#]&&Mod[#+1, Total[Most[Divisors[#]]]]==0&] (* Harvey P. Dale, Jul 28 2024 *)
PROG
(PARI) isok(n) = (n!=1) && !isprime(n) && !frac((n+1)/(sigma(n)-n)); \\ Michel Marcus, Feb 28 2019
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Paolo P. Lava, Feb 22 2019
STATUS
approved