%I #12 Mar 28 2023 07:30:19
%S 1,1,2,4,8,32,64,64,128,256,512,2048,4096,4096,8192,16384,32768,
%T 131072,262144,262144,524288,1048576,2097152,8388608,16777216,
%U 16777216,33554432,67108864,134217728,536870912,1073741824
%N a(n) = 2^A128054(n).
%C A factor in A128056.
%C The signed sequence 1,1,2,-4,-8,-32,-64,-64,-128,256,512... is the Hankel transform of the doubled sequence 1,1,2,2,6,6,... of central binomial coefficients (A128014). - _Paul Barry_, Sep 09 2008
%H <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (2,-4,8,-16,32).
%F G.f.: (-1-16*x^4+4*x^3-4*x^2+x)/((2*x-1)*(4*x^2-2*x+1)*(4*x^2+2*x+1)). - Maksym Voznyy (voznyy(AT)mail.ru), Aug 11 2009
%F Sum_{n>=0} 1/a(n) = 62/21. - _Amiram Eldar_, Mar 28 2023
%Y Cf. A128014, A128054, A128056.
%K easy,nonn
%O 0,3
%A _Paul Barry_, Feb 13 2007