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 A274567 #27 Aug 01 2020 01:16:43 %S A274567 3,81,51,291,1251,339,62499,1971,5201,5001,175781251,7299 %N A274567 Least number k such that k^2-1 is the sum of two nonzero squares in exactly n ways. %C A274567 a(11) > 25*10^5 if it exists. - _Chai Wah Wu_, Jul 23 2020 %C A274567 From _David A. Corneth_, Jul 23 2020: (Start) %C A274567 a(13) <= 17578125001, a(17) <= 610351562499. (End) %e A274567 a(2) = 81 because 81^2 - 1 = 28^2 + 76^2 = 44^2 + 68^2. %Y A274567 Cf. A000404, A005563, A016032, A025426, A050795, A050797, A054994. %K A274567 nonn,more %O A274567 1,1 %A A274567 _Altug Alkan_, Jun 28 2016 %E A274567 a(10) from _Chai Wah Wu_, Jul 22 2020