A274557 - OEIS

%I #18 Feb 10 2021 01:29:11

%S 6,24,25,30,42,54,66,78,102,114,138,174,186,222,246,258,282,304,318,

%T 354,366,402,426,438,474,498,534,582,606,618,642,654,678,762,786,822,

%U 834,894,906,942,978,1002,1038,1074,1086,1146,1158,1182,1194,1266,1338,1362

%N Numbers k such that sigma(k) == 0 (mod k+6).

%H Seiichi Manyama, <a href="/A274557/b274557.txt">Table of n, a(n) for n = 1..10000</a>

%e sigma(6) mod (6+6) = 12 mod 12 = 0.

%p with(numtheory); P:=proc(q,h) local n;  for n from 1 to q do

%p if n+h>0 then if type(sigma(n)/(n+h),integer) then print(n); fi; fi; od; end: P(10^9,6);

%t Select[Range@ 1400, Mod[DivisorSigma[1, #], # + 6] == 0 &] (* _Michael De Vlieger_, Jul 05 2016 *)

%o (PARI) is(n)=sigma(n)%(n+6)==0 \\ _Charles R Greathouse IV_, Jul 16 2016

%Y Cf. A000203, A045770, A067702, A088833, A181598, A274551-A274556, A274558-A274566.

%K nonn

%O 1,1

%A _Paolo P. Lava_, Jul 05 2016