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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A125247 is a subset of this sequence.

LINKS

Table of n, a(n) for n=1..24.

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

Cf. A067702, A274551-A274553, A223609, A274566.

Sequence in context: A254227 A326806 A056050 * A035111 A035282 A075156

Adjacent sequences:  A274551 A274552 A274553 * A274555 A274556 A274557

KEYWORD

nonn

AUTHOR

Paolo P. Lava, Jun 28 2016

EXTENSIONS

a(19)-a(24) from Giovanni Resta

STATUS

approved

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Last modified August 2 09:22 EDT 2021. Contains 346422 sequences. (Running on oeis4.)