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 A145120 #20 Apr 07 2024 17:42:18
%S A145120 38,11438,3454238,1043168438,315033414038,95139047871038,
%T A145120 28731677423639438,8676871442891239238,2620386444075730610438,
%U A145120 791348029239427753113038,238984484443863105709527038
%N A145120 Numbers X such that (X^2-19)/57 is a square.
%H A145120 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (302,-1).
%F A145120 a(n) = 302*a(n-1) - a(n-2).
%F A145120 From _R. J. Mathar_, Nov 27 2011: (Start)
%F A145120 G.f.: -38*x*(-1+x) / ( 1-302*x+x^2 ).
%F A145120 a(n) = 38*A145123(n). (End)
%e A145120 a(1)=38 because 38^2 = 57*25+19.
%t A145120 LinearRecurrence[{302,-1},{38,11438},20] (* _Harvey P. Dale_, Jan 24 2013 *)
%K A145120 easy,nonn
%O A145120 1,1
%A A145120 _Richard Choulet_, Oct 02 2008