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 A273054 #12 Sep 08 2022 08:46:16
%S A273054 4,22,1382,7484,469876,2544538,159756458,865135436,54316725844,
%T A273054 294143503702,18467527030502,100007926123244,6278904873644836,
%U A273054 34002400738399258,2134809189512213738,11560716243129624476,725828845529279026084,3930609520263333922582
%N A273054 Numbers n such that 19*n^2 + 20 is a square.
%H A273054 Colin Barker, <a href="/A273054/b273054.txt">Table of n, a(n) for n = 1..750</a>
%H A273054 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,340,0,-1).
%F A273054 G.f.: 2*x*(2 + 11*x + 11*x^2 + 2*x^3)/(1 - 340*x^2 + x^4).
%F A273054 a(n) = 340*a(n-2) - a(n-4), for n>3.
%t A273054 LinearRecurrence[{0, 340, 0, -1}, {4, 22, 1382, 7484}, 30]
%o A273054 (Magma) I:=[4,22,1382,7484]; [n le 4 select I[n] else 340*Self(n-2)-Self(n-4): n in [1..30]];
%o A273054 (PARI) x='x+O('x^99); Vec(2*x*(2+11*x+11*x^2+2*x^3)/(1-340*x^2+x^4)) \\ _Altug Alkan_, May 14 2016
%Y A273054 Cf. similar sequences listed in A273052.
%K A273054 nonn,easy
%O A273054 1,1
%A A273054 _Vincenzo Librandi_, May 14 2016