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 A156232 #30 Feb 04 2016 06:33:53
%S A156232 0,4,4,16,24,64,112,256,480,1024,1984,4096,8064,16384,32512,65536,
%T A156232 130560,262144,523264,1048576,2095104,4194304,8384512,16777216,
%U A156232 33546240,67108864,134201344,268435456,536838144,1073741824,2147418112
%N A156232 a(n) is the number of induced subgraphs with odd number of edges in the cycle graph C(n).
%C A156232 Essentially the same sequence (see A204696) appears in the Cusick-Stanica paper.
%H A156232 G. C. Greubel, <a href="/A156232/b156232.txt">Table of n, a(n) for n = 2..1000</a>
%H A156232 Thomas W. Cusick, and Pantelimon Stanica, <a href="http://dx.doi.org/10.1016/S0012-365X(02)00354-0">Fast evaluation, weights and nonlinearity of rotation-symmetric functions</a>, Discrete Math. 258 (2002), no. 1-3, 289-301.
%H A156232 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (2, 2, -4).
%F A156232 a(n) = 2^(n-1) - 2^(n/2) if n is even, 2^(n-1) otherwise.
%F A156232 G.f.: 4*x^3*(1-x)/((1-2*x)*(1-2*x^2)). a(n)=2*a(n-1)+2*a(n-2)-4*a(n-3). - _R. J. Mathar_, Feb 10 2009
%F A156232 E.g.f.: 2*(exp(2*x) - cosh(sqrt(2)*x)). - _G. C. Greubel_, Aug 26 2015
%t A156232 RecurrenceTable[{a[n]== 2*a[n-1] + 2*a[n-2] - 4*a[n-3], a[0]==0, a[1]==4, a[2]==4}, a, {n,0,50}] (* _G. C. Greubel_, Aug 26 2015 *)
%t A156232 LinearRecurrence[{2, 2, -4}, {0, 4, 4}, 40] (* _Vincenzo Librandi_, Aug 27 2015 *)
%o A156232 (PARI) Vec(4*x^3*(1-x)/((1-2*x)*(1-2*x^2)) + O(x^40)) \\ _Michel Marcus_, Aug 26 2015
%Y A156232 Cf. A000749, A032085.
%K A156232 nonn
%O A156232 2,2
%A A156232 Alessandro Cosentino (cosenal(AT)gmail.com), Feb 06 2009
%E A156232 More terms from _R. J. Mathar_, Feb 10 2009