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 A231100 #21 Nov 14 2019 21:22:24 %S A231100 4,12,8,24,20,12,40,28,60,16,56,48,36,84,80,72,20,60,112,44,88,24,144, %T A231100 140,132,120,52,180,104,176,168,28,84,156,140,220,60,208,120,32,96, %U A231100 264,260,252,160,240,68,136,224,312,308,36,204,288,180,272,76,364,252,152,352,340,228 %N A231100 Even legs of primitive Pythagorean triples (with multiplicity) sorted with respect to increasing hypotenuse. %C A231100 The primary key is the increasing length of the hypotenuse, A020882. If there is more than one solution with that hypotenuse, the (secondary) sorting key is the (increasing) even leg - that is, the terms go in the increasing order. [Corrected by _Andrey Zabolotskiy_, Oct 31 2019] %C A231100 Only the even legs 'b' of reduced triangles with gcd(a,b,c)=1, a^2+b^2=c^2, a=q^2-p^2, b=2*p*q, c=q^2+p^2, gcd(p,q)=1 are listed. %H A231100 K. G. Stier, <a href="/A231100/b231100.txt">Table of n, a(n) for n = 1..1593</a> %H A231100 Michael Somos, <a href="http://grail.eecs.csuohio.edu/~somos/rtritab.txt"> Pythagorean Triple Table, Reduced integer right triangles</a>, Feb 28, 1998. %H A231100 Wikipedia, <a href="http://en.wikipedia.org/wiki/Pythagorean_triple">Pythagorean Triple</a>. %F A231100 a(n) = sqrt(A020882(n)^2-A180620(n)^2). %e A231100 a(13) = sqrt(A020882(13)^2-A180620(13)^2) = sqrt(85^2-77^2) = sqrt(1296) = 36. %Y A231100 Cf. A020882, A180620. %K A231100 nonn,look %O A231100 1,1 %A A231100 _K. G. Stier_, Nov 03 2013