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 A076602 #10 May 11 2018 01:41:59
%S A076602 7,24,25,312,313,48984,48985,1199765112,1199765113,719718163185951384,
%T A076602 719718163185951385,258997117209879873736794713791709112,
%U A076602 258997117209879873736794713791709113,33539753361514126736178628392779244498735703225085922505721228803623384
%N A076602 a(1)=7, a(n_even)=(a(n-1)^2-1)/2; a(n_odd)=a(n-1)+1.
%C A076602 {7, 24, 25}, {25, 312, 313}, {313, 48984, 48985}... are sides {a<b<c} of the right triangles, with hypotenuse c=b+1.
%t A076602 nxt[{a_,b_}]:={a+1,If[OddQ[a],(b^2-1)/2,b+1]}; Transpose[NestList[nxt,{1,7},15]][[2]] (* _Harvey P. Dale_, Dec 13 2011 *)
%K A076602 easy,nonn
%O A076602 1,1
%A A076602 _Zak Seidov_, Oct 21 2002
%E A076602 More terms from _Harvey P. Dale_, Dec 13 2011