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 A154358 #27 Sep 08 2022 08:45:40
%S A154358 649,99,2049,6499,13449,22899,34849,49299,66249,85699,107649,132099,
%T A154358 159049,188499,220449,254899,291849,331299,373249,417699,464649,
%U A154358 514099,566049,620499,677449,736899,798849,863299,930249
%N A154358 a(n) = 1250*n^2 - 1800*n + 649.
%C A154358 The identity (1250*n^2 - 1800*n + 649)^2 - (25*n^2 - 36*n + 13)*(250*n - 180)^2 = 1 can be written as a(n)^2 - A154355(n)*A154360(n)^2 = 1. See also the third comment in A154357.
%H A154358 Vincenzo Librandi, <a href="/A154358/b154358.txt">Table of n, a(n) for n = 0..10000</a>
%H A154358 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A154358 G.f.: (649 - 1848*x + 3699*x^2)/(1-x)^3. - _R. J. Mathar_, Jan 05 2011
%F A154358 a(n) = 3*a(n-1) -3*a(n-2) +a(n-3).
%F A154358 E.g.f.: (649 - 550*x + 1250*x^2)*exp(x). - _G. C. Greubel_, Sep 14 2016
%t A154358 LinearRecurrence[{3, -3, 1}, {649, 99, 2049}, 50] (* _Vincenzo Librandi_, Feb 21 2012 *)
%o A154358 (PARI) for(n=0, 40, print1(1250*n^2 - 1800*n + 649", ")); \\ _Vincenzo Librandi_, Feb 21 2012
%o A154358 (Magma) [1250*n^2-1800*n+649: n in [0..40]]; // _Bruno Berselli_, Sep 15 2016
%Y A154358 Cf. A154359, A154360, A154361, A154355, A154357.
%K A154358 nonn,easy
%O A154358 0,1
%A A154358 _Vincenzo Librandi_, Jan 08 2009
%E A154358 Offset and one entry corrected by _R. J. Mathar_, Jan 05 2011
%E A154358 Librandi's comment rewritten by _Bruno Berselli_, Dec 13 2011