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A274554
Numbers n such that sigma(n) == 0 (mod n-4).
3
5, 6, 10, 22, 24, 60, 130, 184, 1012, 2272, 18904, 33664, 70564, 85936, 100804, 391612, 527872, 1090912, 17619844, 2147713024, 6800695312, 34360655872, 549759483904, 1661355408388
OFFSET
1,1
COMMENTS
A125247 is a subset of this sequence.
EXAMPLE
sigma(5) mod 5-4 = 6 mod 1 = 0.
MAPLE
with(numtheory); P:=proc(q, h) local n; for n from 1 to q do
if n+h>0 then if type(sigma(n)/(n+h), integer) then print(n); fi; fi; od; end: P(10^9, -4);
MATHEMATICA
k = -4; Select[Range[Abs@ k + 1, 10^7], Mod[DivisorSigma[1, #], # + k] == 0 &] (* Michael De Vlieger, Jul 01 2016 *)
PROG
(Magma) [n: n in [5..2*10^6] | SumOfDivisors(n) mod (n-4) eq 0 ]; // Vincenzo Librandi, Jul 02 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Paolo P. Lava, Jun 28 2016
EXTENSIONS
a(19)-a(24) from Giovanni Resta
STATUS
approved