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%I #11 Apr 11 2024 03:54:40
%S 1,4,6,8,12,22,46,100,216,458,954,1960,3988,8062,16230,32588,65328,
%T 130834,261874,523984,1048236,2096774,4193886,8388148,16776712,
%U 33553882,67108266,134217080,268434756,536870158,1073741014,2147482780
%N a(n) = 2^n-n*(n-3).
%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (5,-9,7,-2).
%F a(n) = +5*a(n-1) -9*a(n-2) +7*a(n-3) -2*a(n-4).
%F G.f.: ( 1-x-5*x^2+7*x^3 ) / ( (2*x-1)*(x-1)^3 ).
%t Table[2^n-n*(n-3),{n,0,5!}]
%Y Cf. A142974, A176776.
%K nonn,easy
%O 0,2
%A _Vladimir Joseph Stephan Orlovsky_, Apr 25 2010
%E Offset corrected by _R. J. Mathar_, Apr 28 2010