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 A065101 #20 Jun 18 2018 03:40:57
%S A065101 2,24,286,3408,40610,483912,5766334,68712096,818778818,9756633720,
%T A065101 116260825822,1385373276144,16508218487906,196713248578728,
%U A065101 2344050764456830,27931895924903232,332838700334381954
%N A065101 a(0) = c, a(1) = p*c^3; a(n+2) = p*c^2*a(n+1) - a(n), for p = 3, c = 2.
%H A065101 Harry J. Smith, <a href="/A065101/b065101.txt">Table of n, a(n) for n = 0..100</a>
%H A065101 J.-P. Ehrmann et al., <a href="http://forumgeom.fau.edu/POLYA/ProblemCenter/POLYA002.html">Problem POLYA002</a>, Integer pairs (x,y) for which (x^2+y^2)/(1+pxy) is an integer.
%H A065101 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>
%H A065101 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (12,-1).
%F A065101 G.f.: 2/(1 - 12*x + x^2). - _Floor van Lamoen_, Feb 07 2002
%F A065101 a(n) = 2*A004191(n). - _R. J. Mathar_, Sep 27 2014
%t A065101 a[0] = c; a[1] = p*c^3; a[n_] := a[n] = p*c^2*a[n - 1] - a[n - 2]; p = 3; c = 2; Table[ a[n], {n, 0, 20} ]
%o A065101 (PARI): polya002(3,2,18). For definition of function polya002 see A052530.
%o A065101 (PARI) { p=3; c=2; k=p*c^2; for (n=0, 100, if (n>1, a=k*a1 - a2; a2=a1; a1=a, if (n, a=a1=k*c, a=a2=c)); write("b065101.txt", n, " ", a) ) } \\ _Harry J. Smith_, Oct 07 2009
%Y A065101 Cf. A052530.
%K A065101 easy,nonn
%O A065101 0,1
%A A065101 _N. J. A. Sloane_, Nov 12 2001