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 A274551 Numbers k such that sigma(k) == 0 (mod k+3). 14
 4, 8925, 32445, 442365 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(5) > 10^8 if it exists. - Felix Fröhlich, Jul 01 2016 No more terms < 6.5*10^14. - Jud McCranie, Dec 02 2019 LINKS Table of n, a(n) for n=1..4. EXAMPLE sigma(4) mod (4+3) = 7 mod 7 = 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, 3); MATHEMATICA Select[Range[10^6], Mod[DivisorSigma[1, #], # + 3] == 0 &] (* Michael De Vlieger, Jul 01 2016 *) PROG (PARI) is(n) = Mod(sigma(n), n+3)==0 \\ Felix Fröhlich, Jul 01 2016 (Magma) [n: n in [1..2*10^6] | SumOfDivisors(n) mod (n+3) eq 0 ]; // Vincenzo Librandi, Jul 02 2016 CROSSREFS Cf. A000203, A067702, A087167, A088834, A274552, A274553, A274554, A274556. Sequence in context: A115050 A072724 A116271 * A257281 A201392 A058417 Adjacent sequences: A274548 A274549 A274550 * A274552 A274553 A274554 KEYWORD nonn,more AUTHOR Paolo P. Lava, Jun 28 2016 STATUS approved

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Last modified December 4 14:48 EST 2023. Contains 367563 sequences. (Running on oeis4.)