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 A239364 #21 Jan 05 2021 19:06:55
%S A239364 38,1442,54758,2079362,78960998,2998438562,113861704358,4323746327042,
%T A239364 164188498723238,6234839205156002,236759701297204838,
%U A239364 8990633810088627842,341407325082070653158,12964487719308596192162,492309126008644584648998,18694782300609185620469762
%N A239364 Numbers n such that (n^2-4)/10 is a square.
%C A239364 Values of x satisfying the Pellian equation x^2 - 10*y^2 = 4.
%H A239364 Colin Barker, <a href="/A239364/b239364.txt">Table of n, a(n) for n = 1..600</a>
%H A239364 Hacène Belbachir, Soumeya Merwa Tebtoub, and László Németh, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL23/Nemeth/nemeth7.html">Ellipse Chains and Associated Sequences</a>, J. Int. Seq., Vol. 23 (2020), Article 20.8.5.
%H A239364 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (38,-1).
%F A239364 a(n) = 2*A078986(n).
%F A239364 a(n) = (19+6*sqrt(10))^(-n)+(19+6*sqrt(10))^n.
%F A239364 a(n) = 38*a(n-1)-a(n-2).
%F A239364 G.f.: -2*x*(x-19) / (x^2-38*x+1).
%e A239364 1442 is in the sequence because (1442^2-4)/10 = 207936 = 456^2.
%t A239364 LinearRecurrence[{38,-1},{38,1442},30] (* _Harvey P. Dale_, Dec 19 2014 *)
%o A239364 (PARI) Vec(-2*x*(x-19)/(x^2-38*x+1) + O(x^100))
%Y A239364 Cf. A078986, A239365.
%K A239364 nonn,easy
%O A239364 1,1
%A A239364 _Colin Barker_, Mar 17 2014