A274558 Numbers k such that sigma(k) == 0 (mod k-6).

7, 13, 14, 20, 30, 45, 76, 630, 688, 2310, 8896, 133888, 537051136, 1631268870

Offset

1,1

Links

Table of n, a(n) for n=1..14.

Example

sigma(7) mod (7-6) = 8 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, -6);

Mathematica

Select[Range[7, 10^6], Mod[DivisorSigma[1, #], # - 6] == 0 &] (* Michael De Vlieger, Jul 05 2016 *)

Crossrefs

Cf. A000203, A045770, A067702, A088833, A181598, A274551-A274557, A274559-A274566.

Sequence in context: A072864 A232437 A275201 * A120100 A308525 A104217

Adjacent sequences: A274555 A274556 A274557 * A274559 A274560 A274561

Keyword

nonn,more

Author

Paolo P. Lava, Jul 05 2016

Extensions

a(13)-a(14) from Giovanni Resta

Status

approved