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 A239365 #16 Aug 04 2022 13:45:52
%S A239365 12,456,17316,657552,24969660,948189528,36006232404,1367288641824,
%T A239365 51920962156908,1971629273320680,74869991424028932,
%U A239365 2843088044839778736,107962475712487563036,4099730989029687616632,155681815107415641868980,5911809243092764703404608
%N A239365 Numbers n such that 10*n^2+4 is a square.
%C A239365 Values of y satisfying the Pellian equation x^2 - 10*y^2 = 4.
%H A239365 Colin Barker, <a href="/A239365/b239365.txt">Table of n, a(n) for n = 1..600</a>
%H A239365 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (38,-1).
%F A239365 a(n) = 2*A078987(n-1).
%F A239365 a(n) = 38*a(n-1)-a(n-2).
%F A239365 G.f.: 12*x / (x^2-38*x+1).
%e A239365 456 is in the sequence because 10*456^2+4 = 2079364 = 1442^2.
%t A239365 LinearRecurrence[{38,-1},{12,456},20] (* _Harvey P. Dale_, Aug 04 2022 *)
%o A239365 (PARI) Vec(12/(x^2-38*x+1) + O(x^100))
%Y A239365 Cf. A078987, A239364.
%K A239365 nonn,easy
%O A239365 1,1
%A A239365 _Colin Barker_, Mar 17 2014