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 A297850 #53 Dec 13 2020 09:56:04 %S A297850 2,2,2,2,2,2,3,2,2,2,3,3,2,3,3,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,2,2,2,2, %T A297850 2,2,2,3,2,2,3,2,2,2,2,3,2,3,2,3,2,2,2,2,2,3,2,2,2,2,2,2,2,2,2,2,2,2, %U A297850 2,2,2,3,2,2,2,2,2,3,2,2,2,3,2,2,3,2,2 %N A297850 Least common prime factor of the members of n-th amicable pair, or 0 if the two members of the pair are coprime. %C A297850 The question whether a(n) = 0 for any n is an open problem. %C A297850 This is different from A171092 (cf. Chernykh link). %C A297850 If a(n) = 0, then A001221(A259180(2*n-1)*A259180(2*n)) > 21 (cf. Hagis, 1975). %H A297850 Amiram Eldar, <a href="/A297850/b297850.txt">Table of n, a(n) for n = 1..10000</a> %H A297850 Sergei Chernykh, <a href="https://sech.me/ap/news.html#20160130">Amicable pairs news</a> %H A297850 Peter Hagis, Jr., <a href="http://www.jstor.org/stable/2690064">On the Number of Prime Factors of a Pair of Relatively Prime Amicable Numbers</a>, Mathematics Magazine, Vol. 48, No. 5 (1975), pp. 263-266. %H A297850 Wikipedia, <a href="https://en.wikipedia.org/wiki/Amicable_numbers">Amicable numbers</a>. %F A297850 a(n) = A297934(A259180(2*n), A259180(2*n-1)). %F A297850 a(n) = A020639(A061469(n)), if A061469(n) > 1 and 0 otherwise. - _Amiram Eldar_, Dec 13 2020 %Y A297850 Cf. A002025, A020639, A061469, A122967, A171092, A259180, A297934. %K A297850 nonn %O A297850 1,1 %A A297850 _Felix Fröhlich_, Jan 10 2018 %E A297850 Offset corrected and more terms added by _Amiram Eldar_, Dec 13 2020