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 A058073 #24 Feb 19 2024 10:29:33 %S A058073 12,14,70,88,180,204,206,220,957,1334,1364,1634,1750,1888,2685,2958, %T A058073 2974,4364,8142,8632,9114,12000,14664,14841,18414,18762,18873,19358, %U A058073 20118,20145,20712,24957,25194,30996,33998,36566,42818,45520,47940 %N A058073 Numbers k such that sigma(k+1) divides sigma(k), where sigma(k) is the sum of positive divisors of k. %C A058073 The quotient (sigma(k)/sigma(k+1)) is equal to 1, 2, 3 or 4 for the first 5000 terms. - _Donovan Johnson_, Oct 21 2012 %H A058073 Donovan Johnson, <a href="/A058073/b058073.txt">Table of n, a(n) for n = 1..5000</a> %e A058073 12 is included because sigma(13) = 14 divides sigma(12) = 28. %t A058073 Select[Range[50000], Mod[DivisorSigma[1, # ], DivisorSigma[1, # + 1]] == 0 &] %K A058073 nonn %O A058073 1,1 %A A058073 _Leroy Quet_, Nov 11 2000 %E A058073 More terms from _Benoit Cloitre_, Jul 27 2002