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 A290985 #25 Dec 13 2020 05:14:53 %S A290985 0,0,0,0,0,0,0,1,1,1,2,3,5,7,8,9,16,22,30,42,57,68,95,133,167,205,257, %T A290985 342,460,605,786,1043,1356,1749,2294,2905,3757,4811,6181,7893,10146, %U A290985 13051,16762,21396,27380,34939,44449,56481,71453,90783,115200,145702,184045,232899,294326,372216 %N A290985 Number of amicable pairs with lesser member at most 2^n. %C A290985 Sergei Chernykh led a BOINC project to find a(64) = 2390655. The project took 7 months and used several hundred CPU-years of computation time. %H A290985 Amiram Eldar, <a href="/A290985/b290985.txt">Table of n, a(n) for n = 1..66</a> (calculated from Chernykh's database) %H A290985 Sergei Chernykh, <a href="https://sech.me/boinc/Amicable/">Amicable Numbers</a>. %o A290985 (PARI) has(n,f=factor(n))=my(t=sigma(f)-n); t>n && sigma(t)==n+t %o A290985 a(n)=my(s); forfactored(k=1,2^n, if(has(k[1],k[2]), s++)); s %Y A290985 Cf. A002025, A066873, A259180. %K A290985 nonn,hard %O A290985 1,11 %A A290985 _Charles R Greathouse IV_, Aug 16 2017