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 A082365 #27 Sep 08 2022 08:45:10
%S A082365 1,11,85,683,5461,43691,349525,2796203,22369621,178956971,1431655765,
%T A082365 11453246123,91625968981,733007751851,5864062014805,46912496118443,
%U A082365 375299968947541,3002399751580331,24019198012642645,192153584101141163
%N A082365 A Jacobsthal number sequence.
%C A082365 A trisection of A024495. - _Paul Curtz_, Nov 18 2007
%H A082365 Vincenzo Librandi, <a href="/A082365/b082365.txt">Table of n, a(n) for n = 0..1000</a>
%H A082365 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (7,8).
%F A082365 a(n) = (4*8^n -(-1)^n)/3.
%F A082365 a(n) = J(3*n+2) = A001045(3*n)/3.
%F A082365 a(n) = 4*A015565(n)+A015565(n+1).
%F A082365 From _Philippe Deléham_, Nov 19 2007: (Start)
%F A082365 a(0)=1, a(1)=11, a(n+1) = 7*a(n) + 8*a(n-1) for n>=1 .
%F A082365 G.f.: (1+4*x)/(1-7*x-8*x^2). (End)
%t A082365 f[n_] := (4*8^n - (-1)^n)/3; Array[f, 20, 0] (* _Robert G. Wilson v_, Aug 13 2011 *)
%t A082365 LinearRecurrence[{7,8},{1,11},20] (* _Harvey P. Dale_, May 06 2012 *)
%o A082365 (Magma) [4*8^n/3-(-1)^n/3: n in [0..30]]; // _Vincenzo Librandi_, Aug 13 2011
%o A082365 (PARI) vector(30, n, n--; (4*8^n -(-1)^n)/3) \\ _G. C. Greubel_, Sep 16 2018
%Y A082365 Cf. A015565, A082311.
%K A082365 easy,nonn
%O A082365 0,2
%A A082365 _Paul Barry_, Apr 09 2003