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 A143647 #19 Sep 08 2022 08:45:37
%S A143647 1,5,28,170,1084,7100,47152,315320,2115856,14221520,95666368,
%T A143647 643790240,4333242304,29169037760,196359046912,1321871638400,
%U A143647 8898817351936,59906997474560,403295993003008,2715005985589760,18277548009831424
%N A143647 a(n) = ((5 + sqrt(3))^n + (5 - sqrt(3))^n)/2.
%C A143647 Binomial transform of A083882. - _R. J. Mathar_, Nov 01 2008
%C A143647 Inverse binomial transform of A147961.
%H A143647 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (10, -22).
%F A143647 From _Philippe Deléham_, _Klaus Brockhaus_ and _R. J. Mathar_, Nov 01 2008: (Start)
%F A143647 a(n) = 10*a(n-1) - 22*a(n-2), a(0)=1, a(1)=5.
%F A143647 G.f.: (1-5x)/(1-10x+22*x^2). (End)
%F A143647 a(n) = (Sum_{k=0..n} A098158(n,k)*5^(2*k)*3^(n-k))/5^n. - _Philippe Deléham_, Nov 06 2008
%t A143647 Simplify[With[{c=Sqrt[3]},Table[((5+c)^n+(5-c)^n)/2,{n,0,25}]]] (* or *) LinearRecurrence[{10,-22},{1,5},25] (* _Harvey P. Dale_, Jun 04 2011 *)
%o A143647 (Magma) Z<x>:= PolynomialRing(Integers()); N<r3>:=NumberField(x^2-3); S:=[ ((5+r3)^n+(5-r3)^n)/2: n in [0..20] ]; [ Integers()!S[j]: j in [1..#S] ]; // _Klaus Brockhaus_, Nov 01 2008
%Y A143647 Cf. A083882, A147961, A098158.
%K A143647 nonn
%O A143647 0,2
%A A143647 Al Hakanson (hawkuu(AT)gmail.com), Oct 27 2008
%E A143647 More terms from _Klaus Brockhaus_ and _R. J. Mathar_, Nov 01 2008
%E A143647 Edited by _Klaus Brockhaus_, Jul 15 2009