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 A170933 #28 Aug 07 2021 18:20:46
%S A170933 7,8,9,12,16,21,29,41,58,83,120,174,253,369,539,788,1153,1688,2472,
%T A170933 3621,5305,7773,11390,16691,24460,35846,52533,76989,112831,165360,
%U A170933 242345,355172,520528,762869,1118037
%N A170933 a(n) = A000930(n) + A000930(n+3) + 4.
%H A170933 G. C. Greubel, <a href="/A170933/b170933.txt">Table of n, a(n) for n = 0..1000</a>
%H A170933 Z. Skupien, <a href="http://dx.doi.org/10.1016/j.disc.2008.11.003">Sparse Hamiltonian 2-decompositions together with exact count of numerous Hamiltonian cycles</a>, Discr. Math., 309 (2009), 6382-6390.
%H A170933 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,1,-1).
%F A170933 G.f.: (7-6*x-5*x^3)/(1-2*x+x^2-x^3+x^4). - _Colin Barker_, Dec 30 2011
%F A170933 a(n) = a(n-1) + a(n-3) - 4 for n>2. - _Greg Dresden_, Feb 09 2020
%t A170933 CoefficientList[Series[(7 - 6*x - 5*x^3)/(1 - 2*x + x^2 - x^3 + x^4), {x, 0, 50}], x] (* _G. C. Greubel_, Apr 26 2017 *)
%t A170933 LinearRecurrence[{2,-1,1,-1},{7,8,9,12},40] (* _Harvey P. Dale_, Aug 07 2021 *)
%o A170933 (PARI) x='x+O('x^50); Vec((7 - 6*x - 5*x^3)/(1 - 2*x + x^2 - x^3 + x^4)) \\ _G. C. Greubel_, Apr 26 2017
%K A170933 nonn,easy
%O A170933 0,1
%A A170933 _N. J. A. Sloane_, Feb 10 2010