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 A165312 #16 Sep 02 2021 04:02:07
%S A165312 1,5,30,205,1505,11430,88105,683405,5314830,41378005,322287305,
%T A165312 2510710230,19560629905,152399173205,1187375157630,9251147403805,
%U A165312 72078242501105,561581982417030,4375445744059705,34090353624231005
%N A165312 a(0)=1, a(1)=5, a(n)=11*a(n-1)-25*a(n-2) for n>1.
%C A165312 a(n)/a(n-1) tends to (11+sqrt(21))/2 = 7.79128784...
%C A165312 For n>=2, a(n) equals 5^n times the permanent of the (2n-2)X(2n-2) tridiagonal matrix with 1/sqrt(5)'s along the main diagonal, and 1's along the superdiagonal and the subdiagonal. [_John M. Campbell_, Jul 08 2011]
%H A165312 Indranil Ghosh, <a href="/A165312/b165312.txt">Table of n, a(n) for n = 0..1119</a>
%H A165312 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-25).
%F A165312 G.f.: (1-6x)/(1-11x+25x^2).
%F A165312 a(n) = Sum_{k=0..n} A165253(n,k)*5^(n-k).
%F A165312 a(n) = ((21-sqrt(21))*(11+sqrt(21))^n+(21+sqrt(21))*(11-sqrt(21))^n )/(42*2^n). [_Klaus Brockhaus_, Sep 26 2009]
%t A165312 LinearRecurrence[{11,-25},{1,5},30] (* _Harvey P. Dale_, Oct 02 2016 *)
%Y A165312 Cf. A165253.
%K A165312 nonn
%O A165312 0,2
%A A165312 _Philippe Deléham_, Sep 14 2009