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 A097498 #23 May 17 2025 05:57:07 %S A097498 1,2,4,8,10,12,16,18,20,24,32,40,44,56,64,88,104,120,128,136,152,184, %T A097498 196,224,234,256,368,464,512,650,672,752,884,992,1024,1504,1888,1952, %U A097498 2048,2144,2272,2528,3724,4096,5624,8192,8384,9112,11096,12224,13736 %N A097498 Numbers k divisible by their abundance sigma(k) - 2*k. %H A097498 Amiram Eldar, <a href="/A097498/b097498.txt">Table of n, a(n) for n = 1..417</a> (terms 1..348 from Charles R Greathouse IV) %H A097498 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Abundance.html">Abundance</a>. %t A097498 Select[Range[15000],Divisible[#,DivisorSigma[1,#]-2#]&]//Quiet (* _Harvey P. Dale_, Mar 15 2018 *) %o A097498 (PARI) is(n)=my(t=sigma(n)-2*n); t && n%t==0 \\ _Charles R Greathouse IV_, Dec 12 2014 %Y A097498 Cf. A000079 (subsequence), A033879, A033880. %Y A097498 Disjoint union of A153501 and A271816. %Y A097498 Cf. also A379236. %K A097498 nonn %O A097498 1,2 %A A097498 _Reinhard Zumkeller_, Aug 24 2004