This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A274553 #22 Jun 29 2025 11:08:12 %S A274553 9,56,368,780,836,2352,11096,17816,45356,77744,91388,128768,254012, %T A274553 388076,430272,2087936,2291936,13174976,29465852,35021696,45335936, %U A274553 120888092,184773312,260378492,381236216,775397948,3381872252,4856970752,6800228816,8589344768,44257207676,114141404156,1461083549696,1471763808896,2199013818368 %N A274553 Numbers k such that sigma(k) == 0 (mod k+4). %e A274553 sigma(9) mod 9+4 = 13 mod 13 = 0. %t A274553 k = 4; Select[Range[Abs@ k + 1, 10^6], Mod[DivisorSigma[1, #], # + k] == 0 &] (* _Michael De Vlieger_, Jul 01 2016 *) %o A274553 (Magma) [n: n in [1..2*10^6] | SumOfDivisors(n) mod (n+4) eq 0 ]; // _Vincenzo Librandi_, Jul 02 2016 %Y A274553 Cf. A045770, A067702, A088833, A181598, A274551, A274552, A274554-A274566. %K A274553 nonn %O A274553 1,1 %A A274553 _Paolo P. Lava_, Jun 28 2016 %E A274553 a(18)-a(35) from _Giovanni Resta_