A274553 Numbers n such that sigma(n) == 0 (mod n+4).

9, 56, 368, 780, 836, 2352, 11096, 17816, 45356, 77744, 91388, 128768, 254012, 388076, 430272, 2087936, 2291936, 13174976, 29465852, 35021696, 45335936, 120888092, 184773312, 260378492, 381236216, 775397948, 3381872252, 4856970752, 6800228816, 8589344768, 44257207676, 114141404156, 1461083549696, 1471763808896, 2199013818368

Offset

1,1

Links

Table of n, a(n) for n=1..35.

Example

sigma(9) mod 9+4 = 13 mod 13 = 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, 10^6], Mod[DivisorSigma[1, #], # + k] == 0 &] (* Michael De Vlieger, Jul 01 2016 *)

Prog

(Magma) [n: n in [1..2*10^6] | SumOfDivisors(n) mod (n+4) eq 0 ]; // Vincenzo Librandi, Jul 02 2016

Crossrefs

Cf. A045770, A067702, A088833, A181598, A274551, A274552, A274554-A274566.

Sequence in context: A034362 A037711 A037613 * A221801 A131468 A231970

Adjacent sequences: A274550 A274551 A274552 * A274554 A274555 A274556

Keyword

nonn

Author

Paolo P. Lava, Jun 28 2016

Extensions

a(18)-a(35) from Giovanni Resta

Status

approved