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 A161940 #19 Sep 08 2022 08:45:45
%S A161940 3,17,101,619,3867,24433,155389,991931,6345363,40639217,260448821,
%T A161940 1669786219,10707539307,68670310033,440429696269,2824879831931,
%U A161940 18118915305123,116216916916817,745434117150341,4781352082416619
%N A161940 a(n) = ((3+sqrt(2))*(5+sqrt(2))^n + (3-sqrt(2))*(5-sqrt(2))^n)/2.
%C A161940 Fifth binomial transform of A162255.
%H A161940 Muniru A Asiru, <a href="/A161940/b161940.txt">Table of n, a(n) for n = 0..256</a>
%H A161940 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (10, -23).
%F A161940 a(n) = 10*a(n-1) - 23*a(n-2) for n > 1; a(0) = 3, a(1) = 17.
%F A161940 G.f.: (3-13*x)/(1-10*x+23*x^2).
%p A161940 a[0] := 3: a[1] := 17: for n from 2 to 20 do a[n] := 10*a[n-1]-23*a[n-2] end do: seq(a[n], n = 0 .. 20); # _Emeric Deutsch_, Jun 27 2009
%t A161940 LinearRecurrence[{10,-23},{3,17},30] (* _Harvey P. Dale_, Oct 05 2012 *)
%o A161940 (Magma) Z<x>:=PolynomialRing(Integers()); N<r>:=NumberField(x^2-2); S:=[ ((3+r)*(5+r)^n+(3-r)*(5-r)^n)/2: n in [0..19] ]; [ Integers()!S[j]: j in [1..#S] ]; // _Klaus Brockhaus_, Jul 01 2009
%o A161940 (GAP) a := [3, 17];; for n in [3..10^2] do a[n] := 10*a[n-1] - 23*a[n-2]; od; a; # _Muniru A Asiru_, Feb 02 2018
%o A161940 (PARI) x='x+O('x^30); Vec((3-13*x)/(1-10*x+23*x^2)) \\ _G. C. Greubel_, Aug 17 2018
%Y A161940 Cf. A162255, A161939 (fourth binomial transform of A162255).
%K A161940 nonn
%O A161940 0,1
%A A161940 Al Hakanson (hawkuu(AT)gmail.com), Jun 22 2009
%E A161940 Edited and extended beyond a(4) by _Klaus Brockhaus_, Jul 01 2009
%E A161940 Extended by _Emeric Deutsch_, Jun 27 2009