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 A273930 #12 Feb 16 2025 08:33:36 %S A273930 59509850400,68763895200,72747675000,88410722400,88021533600, %T A273930 89894684880,89894684880,90391981680,102481394400 %N A273930 Amicable 5-tuples: (x1,...,x5) such that sigma(x1)=...=sigma(x5)=x1+...+x5, x1<x2<x3<x4<x5. Sequence gives x2 numbers. %C A273930 The 5-tuple starting with 53542288800 was given by Donovan Johnson. The common value of sigma(x) is 294821130240. %C A273930 A larger 5-tuple, (55766707476480, 56992185169920, 57515254917120, 57754372515840, 57829096765440), was found by Michel Marcus on Dec 09 2013. The common value of sigma(x) is 285857616844800. %C A273930 A still larger example (227491164588441600, 228507506351308800, 229862628701798400, 230878970464665600, 243752632794316800), probably the first one to be published, had been found by Yasutoshi Kohmoto in 2008, cf. link to SeqFan post. %C A273930 Other terms from John Cerkan. %C A273930 There are different definitions for amicable k-tuples, cf. link to MathWorld. %H A273930 John Cerkan, <a href="/A273930/a273930.txt">More terms, with gaps.</a> %H A273930 Yasutoshi Kohmoto, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2008-November/000217.html">Sigma(x)=Sigma(y)=Sigma(z)=Sigma(u)=Sigma(v)=x+y+z+u+v</a>, SeqFan list, Nov 23 2008 %H A273930 Yasutoshi Kohmoto, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2013-December/012089.html">Sigma(x)=Sigma(y)=Sigma(z)=Sigma(u)=Sigma(v)=x+y+z+u+v</a>, SeqFan list, Dec 09 2013 %H A273930 Eric W. Weisstein, <a href="https://mathworld.wolfram.com/AmicableTriple.html">Amicable Triple</a>. From MathWorld--A Wolfram Web Resource. %Y A273930 Cf. A233553, A273928, A273931, A273933, A273934, A273936 (5-tuples). %Y A273930 Cf. A036471 - A036474 and A116148 (quadruples). %Y A273930 Cf. A125490 - A125492 and A137231 (triples). %K A273930 nonn,more %O A273930 1,1 %A A273930 _John Cerkan_, Jun 04 2016