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 A279269 #39 Apr 22 2019 13:56:36
%S A279269 1,7,53,391,2865,20967,153413,1122471,8212705,60089287,439650773,
%T A279269 3216759751,23535824145,172202794407,1259943234533,9218531904231,
%U A279269 67448539061185,493495652968327,3610722528440693,26418301962683911,193292803059267825,1414250914660723047
%N A279269 a(n) = floor( (4 + sqrt(11))^n ).
%C A279269 All numbers are odd.
%H A279269 Olimpiada Matemática Española, <a href="http://www.olimpiadamatematica.es/platea.pntic.mec.es/_csanchez/olimpcompendi.htm">Si n es un número natural, demostrar que la parte entera de (4 + sqrt(11))^n es un número impar</a> (in Spanish), Problem 26/3 (1990), page 26.
%H A279269 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (9,-13,5).
%F A279269 O.g.f.: (1 - 2*x + 3*x^2)/((1 - x)*(1 - 8*x + 5*x^2)). - _Ilya Gutkovskiy_, Dec 13 2016
%F A279269 E.g.f.: exp((4 + sqrt(11))*x) + exp((4 - sqrt(11))*x) - exp(x). - _Bruno Berselli_, Dec 14 2016
%F A279269 a(n) = 9*a(n-1) - 13*a(n-2) + 5*a(n-3) for n>2.
%F A279269 a(n) = 8*a(n-1) - 5*a(n-2) + 2 for n>1.
%F A279269 a(n) = (4 + sqrt(11))^n + (4 - sqrt(11))^n - 1. - _Bruno Berselli_, Dec 13 2016
%t A279269 Floor[(4+Sqrt[11])^Range[0,30]] (* or *) LinearRecurrence[{9,-13,5},{1,7,53},30] (* _Harvey P. Dale_, Apr 22 2019 *)
%K A279269 nonn,easy
%O A279269 0,2
%A A279269 _Philippe Deléham_, Dec 13 2016