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Expansion of 1/(1-2x-x^2+4x^4).
1

%I #11 Jul 30 2024 17:45:30

%S 1,2,5,12,25,54,113,232,477,970,1965,3972,8001,16094,32329,64864,

%T 130053,260594,521925,1044988,2091689,4185990,8375969,16757976,

%U 33525165,67064346,134149981,268332404,536714129,1073503278,2147120761

%N Expansion of 1/(1-2x-x^2+4x^4).

%C Diagonal sums of number triangle A122438. Convolution of A052947 and 2^n.

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,1,0,-4).

%t CoefficientList[Series[1/(1 - 2x - x^2 + 4x^4), {x, 0, 31}], x] (* _Robert G. Wilson v_, Sep 14 2006 *)

%t LinearRecurrence[{2,1,0,-4},{1,2,5,12},40] (* _Harvey P. Dale_, Jul 30 2024 *)

%K easy,nonn

%O 0,2

%A _Paul Barry_, Sep 05 2006

%E More terms from _Robert G. Wilson v_, Sep 14 2006