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 A042200 #29 Jul 09 2025 02:23:58
%S A042200 25,1251,62575,3130001,156562625,7831261251,391719625175,
%T A042200 19593812520001,980082345625225,49023711093781251,2452165637034687775,
%U A042200 122657305562828170001,6135317443778443187825,306888529494484987561251
%N A042200 Numerators of continued fraction convergents to sqrt(626).
%H A042200 Vincenzo Librandi, <a href="/A042200/b042200.txt">Table of n, a(n) for n = 0..200</a>
%H A042200 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>
%H A042200 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (50, 1).
%F A042200 a(n) = 50*a(n-1)+a(n-2) for n>1; a(0)=25, a(1)=1251. G.f.: (25+x)/(1-50*x-x^2). [_Philippe Deléham_, Nov 23 2008]
%t A042200 Numerator[Convergents[Sqrt[626], 30]] (* _Harvey P. Dale_, Jul 15 2012 *)
%t A042200 CoefficientList[Series[(25 + x)/(1 - 50 x - x^2), {x, 0, 20}], x] (* _Vincenzo Librandi_, Nov 19 2013 *)
%o A042200 (Magma) I:=[25,1251]; [n le 2 select I[n] else 50*Self(n-1)+Self(n-2): n in [1..30]]; // _Vincenzo Librandi_, Nov 19 2013
%Y A042200 Cf. A042201.
%K A042200 nonn,cofr,frac,easy
%O A042200 0,1
%A A042200 _N. J. A. Sloane_