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 A076672 #13 Mar 12 2014 00:53:07
%S A076672 6,8,15,20,21,28,45,60,63,84,112,180,189,252,275,660,693,924,1232,
%T A076672 1326,1768,1974,2632,4026,5368,6405,8200,8319,11092,11715,15620,16401,
%U A076672 19720,20706,20880,20910,24752,24960,25300,26565,29716
%N A076672 Smallest a(n)>a(n-1) such that a(n)^2+a(n-1)^2 is a perfect square, a(1)=6.
%C A076672 The sequence is infinite.
%t A076672 Clear[nxt]; nxt[n_]:=Module[{i=n+1},While[!IntegerQ[Sqrt[n^2+i^2]],i++]; i]; NestList[nxt,6,40] (* _Harvey P. Dale_, Dec 03 2010 *)
%Y A076672 Cf. A076600, A076671 (starting at 5).
%K A076672 nonn
%O A076672 1,1
%A A076672 _Zak Seidov_, Oct 25 2002