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 A122742 #11 Jul 26 2019 09:40:08 %S A122742 0,0,1,3,6,16,34,80,172,384,824,1792,3824,8192,17376,36864,77760, %T A122742 163840,343936,720896,1507072,3145728,6553088,13631488,28310528, %U A122742 58720256,121632768,251658240,520089600,1073741824,2214584320,4563402752,9395224576,19327352832,39728414720,81604378624 %N A122742 Numbers of polypentagons with two connected internal vertices (see Cyvin et al. for precise definition). %H A122742 S. J. Cyvin et al., <a href="https://doi.org/10.1021/ci00013a027">Theory of polypentagons</a>, J. Chem. Inf. Comput. Sci., 33 (1993), 466-474 %H A122742 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-2,-8,8). %F A122742 G.f.: x^6*(x-1)*(2*x^3-4*x^2+1) / ((2*x-1)^2*(2*x^2-1)). - _Colin Barker_, Aug 29 2013 %F A122742 a(n) = A001787(n+1)/256 - 2^(n-7) - A077957(n)/16, n>6. - _R. J. Mathar_, Jul 26 2019 %K A122742 nonn,easy %O A122742 4,4 %A A122742 _N. J. A. Sloane_, Sep 24 2006