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%I #24 Mar 16 2024 14:25:23
%S 1,2,12,58,248,1014,4084,16370,65520,262126,1048556,4194282,16777192,
%T 67108838,268435428,1073741794,4294967264,17179869150,68719476700,
%U 274877906906,1099511627736,4398046511062,17592186044372,70368744177618
%N a(n) = 2^(2*n) - 2*n.
%H Guo-Niu Han, <a href="/A196265/a196265.pdf">Enumeration of Standard Puzzles</a>, 2011. [Cached copy]
%H Guo-Niu Han, <a href="https://arxiv.org/abs/2006.14070">Enumeration of Standard Puzzles</a>, arXiv:2006.14070 [math.CO], 2020.
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (6,-9,4).
%F From _Colin Barker_, May 29 2012: (Start)
%F a(n) = 6*a(n-1) - 9*a(n-2) + 4*a(n-3).
%F G.f.: (1 - 4*x + 9*x^2)/((1 - x)^2*(1 - 4*x)). (End)
%p seq(2^(2*n)-2*n, n=0..20);
%t Table[2^(2n)-2n,{n,0,40}] (* or *) LinearRecurrence[{6,-9,4},{1,2,12},40] (* _Harvey P. Dale_, May 27 2021 *)
%Y Bisection of A000325.
%K nonn,easy
%O 0,2
%A _Jorge Coveiro_, Dec 26 2004
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