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 A146966 #26 Sep 08 2022 08:45:38
%S A146966 1,6,43,342,2857,24366,209539,1807854,15617617,134983638,1166892763,
%T A146966 10088187654,87218361721,754062898686,6519422294323,56365243469982,
%U A146966 487319675104417,4213244040623526,36426657909454219,314935817735368374
%N A146966 a(n) = ((6 + sqrt(7))^n + (6 - sqrt(7))^n) / 2.
%H A146966 Robert Israel, <a href="/A146966/b146966.txt">Table of n, a(n) for n = 0..1000</a>
%H A146966 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (12,-29).
%F A146966 a(n) = 12*a(n-1)-29*a(n-2), a(0)=1, a(1)=6. - _Philippe Deléham_, Nov 05 2008
%F A146966 G.f.: (1-6*x)/(1-12*x+29*x^2). - _Klaus Brockhaus_, Nov 05 2008
%F A146966 a(n) = (Sum_{k=0..n} A098158(n,k)*6^(2*k)*7^(n-k))/6^n. - _Philippe Deléham_, Nov 06 2008
%F A146966 E.g.f.: exp(6*x)*cosh(sqrt(7)*x). - _G. C. Greubel_, Jan 08 2020
%e A146966 a(3) = ((6 + sqrt(7))^3 + (6 - sqrt(7))^3) / 2 = 342.
%p A146966 f:= gfun:-rectoproc({a(n) = 12*a(n-1)-29*a(n-2), a(0)=1, a(1)=6},a(n),remember):
%p A146966 map(f, [$0..100]); # _Robert Israel_, Feb 01 2016
%t A146966 RecurrenceTable[{a[1]==1, a[2]==6, a[n]== 12 a[n-1] - 29 a[n-2]}, a, {n, 20}] (* _Vincenzo Librandi_, Jan 31 2016 *)
%t A146966 LinearRecurrence[{12,-29},{1,6},20] (* _Harvey P. Dale_, Apr 17 2018 *)
%o A146966 (Magma) Z<x>:= PolynomialRing(Integers()); N<r7>:=NumberField(x^2-7); S:=[ ((6+r7)^n+(6-r7)^n)/2: n in [0..19] ]; [ Integers()!S[j]: j in [1..#S] ]; // _Klaus Brockhaus_, Nov 05 2008
%o A146966 (Magma) I:=[1,6]; [n le 2 select I[n] else 12*Self(n-1)-29*Self(n-2): n in [1..30]]; // _Vincenzo Librandi_, Jan 31 2016
%o A146966 (PARI) Vec((1-6*x)/(1-12*x+29*x^2) + O(x^30)); \\ _Michel Marcus_, Jan 31 2016
%o A146966 (Sage)
%o A146966 def A146966_list(prec):
%o A146966 P.<x> = PowerSeriesRing(ZZ, prec)
%o A146966 return P( (1-6*x)/(1-12*x+29*x^2) ).list()
%o A146966 A146966_list(20) # _G. C. Greubel_, Jan 08 2020
%o A146966 (GAP) a:=[1,6];; for n in [3..20] do a[n]:12*a[n-1]-29*a[n-2]; od; a; # _G. C. Greubel_, Jan 08 2020
%K A146966 nonn
%O A146966 0,2
%A A146966 Al Hakanson (hawkuu(AT)gmail.com), Nov 03 2008
%E A146966 Extended beyond a(7) by _Klaus Brockhaus_, Nov 05 2008
%E A146966 Typo in name corrected by _Sean Reeves_, Dec 19 2015