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A274559 Numbers n such that sigma(n)==0 (mod n+7). 2
8, 272, 7232, 30848, 516608, 134094848, 2146992128 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..7.

EXAMPLE

sigma(8) mod (8+7) = 15 mod 15 = 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, 7);

MATHEMATICA

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

CROSSREFS

Cf. A141546, A045770, A067702, A088833, A181598, A274551-A274558, A274560-A274566.

Sequence in context: A230590 A300047 A129424 * A159496 A045479 A179570

Adjacent sequences:  A274556 A274557 A274558 * A274560 A274561 A274562

KEYWORD

nonn,more

AUTHOR

Paolo P. Lava, Jul 05 2016

EXTENSIONS

a(6)-a(7) from Giovanni Resta, Jul 05 2016

STATUS

approved

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Last modified June 25 23:52 EDT 2019. Contains 324367 sequences. (Running on oeis4.)