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 A275996 #45 Aug 27 2025 09:48:37 %S A275996 108,220,6808,8968,14008,24448,66928,552568,786208,1020568,5303488, %T A275996 8229568,10001848,133685248,499722448,2608895488,4733164768, %U A275996 7163795488,13707973408,14468025568,16122444736,27339731968,34351218688,34672397728,35371084288,69657461248 %N A275996 Numbers n whose abundance is 64: sigma(n) - 2n = 64. %C A275996 Any term x = a(m) of this sequence can be used with any term y of A275997 to satisfy the property (sigma(x)+sigma(y))/(x+y) = 2, which is a necessary (but not sufficient) condition for two numbers to be amicable. %C A275996 The smallest amicable pair is (220, 284) = (a(2), A275997(2)) = (A063990(1), A063990(2)), where 284 - 220 = 64 is the abundance of 220 and the deficiency of 284. %C A275996 The amicable pair (66928, 66992) = (a(7), A275997(11)) = (A063990(18), A063990(19)), and 66992 - 66928 = 64 is the abundance of 66928 and the deficiency of 66992. %H A275996 Max Alekseyev, <a href="/A275996/b275996.txt">Table of n, a(n) for n = 1..63</a> %e A275996 a(1) = 108, since sigma(108) - 2*108 = 280 - 216 = 64. %o A275996 (PARI) isok(n) = sigma(n) - 2*n == 64; \\ _Michel Marcus_, Dec 30 2016 %Y A275996 Subsequence of A005101. %Y A275996 Cf. A002025, A063990, A275997, A088831, A088832, A088833, A141547, A175989, A275701, A066539, A259180. %K A275996 nonn,changed %O A275996 1,1 %A A275996 _Timothy L. Tiffin_, Aug 16 2016 %E A275996 a(14)-a(15) from _Michel Marcus_, Dec 30 2016 %E A275996 a(16)-a(21) from _Lars Blomberg_, Jan 12 2017 %E A275996 Terms a(22) onward from _Max Alekseyev_, Aug 27 2025