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 A176900 #14 Feb 26 2022 04:24:18
%S A176900 1,-4,-24,-32,80,384,448,-1024,-4608,-5120,11264,49152,53248,-114688,
%T A176900 -491520,-524288,1114112,4718592,4980736,-10485760,-44040192,
%U A176900 -46137344,96468992,402653184,419430400,-872415232,-3623878656,-3758096384
%N A176900 a(n) = sin((2*n+5)*Pi/6)*(n+1)*2^(n+1).
%H A176900 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-12,16,-16).
%F A176900 Sum_{k>=0} 1/a(k) = log(2), from log((1+x)/(1-x+x^2)) at x=1/2.
%F A176900 G.f.: (1-8*x+4*x^2)/(1-2*x+4*x^2)^2.
%F A176900 Sum_{n>=0} (-1)^n/a(n) = log(7/2). - _Amiram Eldar_, Feb 26 2022
%t A176900 Table[Sin[(2*n + 5)*Pi/6]*(n + 1)*2^(n + 1), {n, 0, 27}] (* _Amiram Eldar_, Feb 26 2022 *)
%o A176900 (PARI) a(n)=[1,-1,-2,-1,1,2][n%6+1]*(n+1)*2^n
%Y A176900 Cf. A002162.
%K A176900 sign
%O A176900 0,2
%A A176900 _Jaume Oliver Lafont_, Apr 28 2010