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 A291778 #27 Sep 29 2022 03:27:55
%S A291778 1,1,2,4,4,8,16,16,32,64,64,128,256,256,512,1024,1024,2048,4096,4096,
%T A291778 8192,16384,16384,32768,65536,65536,131072,262144,262144,524288,
%U A291778 1048576,1048576,2097152,4194304,4194304,8388608,16777216,16777216,33554432,67108864,67108864
%N A291778 a(n) = 2^floor(2*n/3).
%H A291778 Robert Israel, <a href="/A291778/b291778.txt">Table of n, a(n) for n = 0..4978</a>
%H A291778 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,4).
%F A291778 a(n) = 2^A004523(n).
%F A291778 G.f.: (1+x+2*x^2)/(1-4*x^3). - _Robert Israel_, Sep 01 2017
%F A291778 From _Amiram Eldar_, Sep 29 2022: (Start)
%F A291778 Sum_{n>=0} 1/a(n) = 10/3.
%F A291778 Sum_{n>=0} (-1)^n/a(n) = 2/5. (End)
%p A291778 seq(2^floor(2*n/3),n=0..100); # _Robert Israel_, Sep 01 2017
%t A291778 LinearRecurrence[{0, 0, 4}, {1, 1, 2}, 41] (* _Jean-François Alcover_, Apr 02 2019 *)
%Y A291778 Cf. A004523, A291779.
%K A291778 nonn
%O A291778 0,3
%A A291778 _Don Reble_ and _N. J. A. Sloane_, Aug 31 2017