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 A099831 #11 Feb 16 2025 08:32:55 %S A099831 60,84,90,132,144,210,264,270,288,300,312,330,390,408,432,440,450,456, %T A099831 462,468,510,520,546,552,570,576,588,612,616,680,684,690,700,728,760, %U A099831 770,800,810,816,828,870,910,912,918,920,952,1044,1064,1100,1104,1116 %N A099831 Perimeters of Pythagorean triangles that can be constructed in exactly 2 different ways. %H A099831 Ray Chandler, <a href="/A099831/b099831.txt">Table of n, a(n) for n = 1..10000</a> %H A099831 Ron Knott, <a href="http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Pythag/pythag.html">Pythagorean Triples and Online Calculators</a> %H A099831 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PythagoreanTriple.html">Pythagorean Triple.</a> %H A099831 <a href="/index/Ps#PyTrip">Index entries related to Pythagorean Triples.</a> %e A099831 a(1)=60 = 10+24+26 = 15+20+25; a(2)=84 = 12+35+37 = 21+28+35. %Y A099831 Cf. A098714, A099382, A099383, A156687. %K A099831 nonn %O A099831 1,1 %A A099831 _Hugo Pfoertner_, Oct 27 2004