Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #29 Dec 26 2023 07:02:57
%S 20,801,32060,1283201,51360100,2055687201,82278848140,3293209612801,
%T 131810663360180,5275719744020001,211160600424160220,
%U 8451699736710428801,338279150068841312260,13539617702490362919201,541922987249683358080300
%N Numerators of continued fraction convergents to sqrt(401).
%H Vincenzo Librandi, <a href="/A041760/b041760.txt">Table of n, a(n) for n = 0..200</a>
%H Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>
%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (40,1).
%F a(n) = 40*a(n-1)+a(n-2) for n>1, a(0)=20, a(1)=801. G.f.: (20+x)/(1-40*x-x^2). [_Philippe Deléham_, Nov 23 2008]
%t Numerator[Convergents[Sqrt[401], 30]] (* _Vincenzo Librandi_, Nov 07 2013 *)
%Y Cf. A041761, A040380.
%K nonn,cofr,frac,easy,less
%O 0,1
%A _N. J. A. Sloane_.