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 A099212 #12 Mar 19 2025 21:14:23
%S A099212 1,0,0,4,-8,16,-16,0,64,-192,384,-512,256,1024,-4096,9216,-14336,
%T A099212 12288,12288,-81920,212992,-376832,425984,0,-1507328,4718592,-9437184,
%U A099212 12845056,-6815744,-24117248,99614720,-226492416,356515840,-314572800,-276824064,1979711488
%N A099212 a(n) = -2*a(n-1) + 4*a(n-3), with a(0) = 1, a(1) = a(2) = 0.
%C A099212 Binomial transform is A099213.
%H A099212 Andrew Howroyd, <a href="/A099212/b099212.txt">Table of n, a(n) for n = 0..1000</a>
%H A099212 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-2,0,4).
%F A099212 G.f.: (1 + 2*x)/(1 + 2*x - 4*x^3).
%t A099212 LinearRecurrence[{-2,0,4},{1,0,0},40] (* _Harvey P. Dale_, May 02 2019 *)
%Y A099212 Cf. A099211.
%K A099212 easy,sign
%O A099212 0,4
%A A099212 _Paul Barry_, Oct 06 2004
%E A099212 a(31) onwards from _Andrew Howroyd_, Mar 19 2025