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a(n) = 3*a(n-1)-4*a(n-2)+6*a(n-3)-4*a(n-4).
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%I #12 Jan 02 2024 08:58:01

%S 0,1,2,4,10,24,48,92,188,388,772,1524,3060,6164,12308,24532,49108,

%T 98388,196692,393044,786260,1573204,3146068,6290772,12582228,25167188,

%U 50333012,100660564,201323860,402658644,805311828,1610601812,3221214548

%N a(n) = 3*a(n-1)-4*a(n-2)+6*a(n-3)-4*a(n-4).

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (3,-4,6,-4).

%F From _R. J. Mathar_, Apr 25 2008: (Start)

%F G.f.: x*(1-x+2*x^2+2*x^4)/((x-1)*(2*x-1)*(2*x^2+1)).

%F a(n) = 3*2^(n-2)-(-1)^[(n+1)/2]*A016116(n+1)/6-4/3, n > 1. (End)

%K nonn,easy

%O 0,3

%A _Paul Curtz_, Apr 01 2008