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 A340713 #24 Jan 18 2021 03:52:53 %S A340713 37033919,141162839,264995639,596672999,606523679,630777839,791656319, %T A340713 920424119,1060332839,1379454719,1954690919,3799661039,4024838999, %U A340713 4633959959,5393988599,5935994063,8831231639,9866482079,11237657759,11273710139,12266364599,14440498379,14952625379 %N A340713 Numbers k such that sigma(k+1) = 4 * sigma(k). %H A340713 Seiichi Manyama, <a href="/A340713/b340713.txt">Table of n, a(n) for n = 1..40</a> (using A058072 data) %o A340713 (PARI) isok(k) = sigma(k+1) == 4*sigma(k); \\ _Michel Marcus_, Jan 18 2021 %Y A340713 Cf. A000203, A002961, A058072, A067081, A077087, A340715. %K A340713 nonn %O A340713 1,1 %A A340713 _Seiichi Manyama_, Jan 17 2021 %E A340713 a(10)-a(23) from _Seiichi Manyama_ using A058072 data, Jan 17 2021