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 A246911 #15 Sep 08 2022 08:46:09 %S A246911 28,66,348,496,840,920,1320,1416,1602,1770,1896,1920,2040,2280,2556, %T A246911 3000,3360,3720,4440,4920,5456,5640,5826,7080,7392,8010,8040,8128, %U A246911 8298,10528,10680,11424,12768,12840,13080,15108,15504,17880,18120,18720,18840,20832 %N A246911 Numbers n such that sigma(n+sigma(n)) = 4*sigma(n). %e A246911 Number 28 (with sigma(28) = 56) is in sequence because sigma(26+sigma(26)) = sigma(84) = 224 = 4*56. %p A246911 with(numtheory): A246911:=n->`if`(sigma(n+sigma(n)) = 4*sigma(n),n,NULL): seq(A246911(n), n=1..3*10^4); # _Wesley Ivan Hurt_, Sep 07 2014 %o A246911 (Magma) [n:n in[1..10000] | SumOfDivisors(n+SumOfDivisors(n)) eq 4*SumOfDivisors(n)] %o A246911 (PARI) %o A246911 for(n=1,10^4,if(sigma(n+sigma(n))==4*sigma(n),print1(n,", "))) \\ _Derek Orr_, Sep 07 2014 %Y A246911 Cf. A000203, A239050, A246456, A246909, A246910, A246912, A246913, A246914. %K A246911 nonn %O A246911 1,1 %A A246911 _Jaroslav Krizek_, Sep 07 2014