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 A157760 #18 Apr 01 2025 08:44:12
%S A157760 1898,9325,22370,41033,65314,95213,130730,171865,218618,270989,328978,
%T A157760 392585,461810,536653,617114,703193,794890,892205,995138,1103689,
%U A157760 1217858,1337645,1463050,1594073,1730714,1872973,2020850,2174345
%N A157760 a(n) = 2809*n^2 - 1000*n + 89.
%C A157760 The identity (15780962*n^2-5618000*n+500001)^2-(2809*n^2-1000*n+89)*( 297754*n-53000)^2=1 can be written as A157762(n)^2-a(n)*A157761(n)^2=1.
%H A157760 Vincenzo Librandi, <a href="/A157760/b157760.txt">Table of n, a(n) for n = 1..10000</a>
%H A157760 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A157760 G.f.: x*(1898 + 3631*x + 89*x^2)/(1 - x)^3.
%F A157760 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3).
%t A157760 LinearRecurrence[{3,-3,1},{1898,9325,22370},50]
%o A157760 (Magma) I:=[1898, 9325, 22370]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..50]];
%o A157760 (PARI) a(n) = 2809*n^2 - 1000*n + 89;
%Y A157760 Subsequence of A031396, see A157757.
%Y A157760 Cf. A157761, A157762.
%K A157760 nonn,easy
%O A157760 1,1
%A A157760 _Vincenzo Librandi_, Mar 06 2009