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 A165322 #13 Sep 02 2021 04:01:58
%S A165322 1,7,56,497,4711,46312,463841,4688327,47596696,484222417,4931098151,
%T A165322 50239573832,511969798081,5217807853447,53180597695736,
%U A165322 542036380617137,5524696422165991,56310663682250152,573949830547618721
%N A165322 a(0)=1, a(1)=7, a(n)=15*a(n-1)-49*a(n-2) for n>1.
%C A165322 a(n)/a(n-1) tends to (15+sqrt(29))/2=10,192582...
%C A165322 For n>=2, a(n) equals 7^n times the permanent of the (2n-2)X(2n-2) tridiagonal matrix with 1/sqrt(7)'s along the main diagonal, and 1's along the superdiagonal and the subdiagonal. [_John M. Campbell_, Jul 08 2011]
%H A165322 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (15,-49).
%F A165322 G.f.: (1-8x)/(1-15x+49x^2).
%F A165322 a(n) = Sum_{k=0..n} A165253(n,k)*7^(n-k).
%F A165322 a(n) = ((29-sqrt(29))*(15+sqrt(29))^n+(29+sqrt(29))*(15-sqrt(29))^n )/(58*2^n). [_Klaus Brockhaus_, Sep 26 2009]
%t A165322 LinearRecurrence[{15,-49},{1,7},20] (* _Harvey P. Dale_, Jun 04 2021 *)
%Y A165322 Cf. A165253.
%K A165322 nonn
%O A165322 0,2
%A A165322 _Philippe Deléham_, Sep 14 2009