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 A097267 #4 Feb 16 2025 08:32:54 %S A097267 1,3,9,19,21,27,39,33,59,51,75,57,63,103,81,0,93,121,111,99,133,123, %T A097267 181,129,141,153,159,211,147,227,183,171,217,263,271,201,189,219,0, %U A097267 307,237,243,261,249,301,267,367,485,231,291,303,409,309,419,327,297 %N A097267 Least positive integer that is the diagonal of n primitive Pythagorean quadruples, or zero if no such integer exists. %C A097267 First appearance of n in A097266. %C A097267 Conjecture: a(15)=a(38)=0. %H A097267 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PythagoreanQuadruple.html">Pythagorean Quadruple.</a> %Y A097267 Cf. A096907-A096909, A097263-A097266. %K A097267 nonn %O A097267 0,2 %A A097267 _Ray Chandler_, Aug 19 2004