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a(n)=2*A081294(n).
3

%I #8 Jun 29 2023 12:36:37

%S 2,4,16,64,256,1024,4096,16384,65536,262144,1048576,4194304,16777216,

%T 67108864,268435456,1073741824,4294967296,17179869184,68719476736,

%U 274877906944,1099511627776,4398046511104,17592186044416,70368744177664

%N a(n)=2*A081294(n).

%H <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (4).

%F a(n)=A000302(n), n>0.

%F G.f.: 2*(1-2*x)/(1-4*x). [R. J. Mathar, Jul 23 2009]

%F Conjecture: a(n)=A090129(2n+2).

%t CoefficientList[Series[2(1-2x)/(1-4x),{x,0,30}],x] (* or *) Join[{2}, NestList[ 4#&,4,30]] (* _Harvey P. Dale_, Nov 13 2015 *)

%K nonn,easy

%O 0,1

%A _Paul Curtz_, Jan 24 2009

%E Edited and extended by _R. J. Mathar_, Jul 23 2009