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A274556
Numbers k such that sigma(k) == 0 (mod k-5).
3
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.
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
KEYWORD
nonn,more
AUTHOR
Paolo P. Lava, Jun 30 2016
EXTENSIONS
a(15) from Giovanni Resta, Jul 01 2016
STATUS
approved