A274556 Numbers k such that sigma(k) == 0 (mod k-5).

6, 7, 8, 11, 12, 18, 21, 26, 68, 656, 2336, 8768, 133376, 528896, 34360918016

Offset

1,1

Comments

A101223 is a subset of this sequence.

Links

Table of n, a(n) for n=1..15.

Example

sigma(6) (mod 6-5) = 12 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, -5);

Mathematica

n = -5; Select[Range[Abs@ n + 1, 10^6], Mod[DivisorSigma[1, #], # + n] == 0 &] (* Michael De Vlieger, Jul 01 2016 *)

Prog

(Magma) [n: n in [6..2*10^6] | SumOfDivisors(n) mod (n-5) eq 0]; // Vincenzo Librandi, Jul 02 2016

Crossrefs

Cf. A067702, A101223, A223609, A274551-A274554.

Sequence in context: A261752 A248902 A295668 * A066235 A037365 A083340

Adjacent sequences: A274553 A274554 A274555 * A274557 A274558 A274559

Keyword

nonn,more

Author

Paolo P. Lava, Jun 30 2016

Extensions

a(15) from Giovanni Resta, Jul 01 2016

Status

approved