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A098560
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Expansion of e.g.f. (1+4*x)/(1-4*x).
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2
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1, 8, 64, 768, 12288, 245760, 5898240, 165150720, 5284823040, 190253629440, 7610145177600, 334846387814400, 16072626615091200, 835776583984742400, 46803488703145574400, 2808209322188734464000, 179725396620079005696000
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = 2*4^n*n! - 0^n.
Sum_{n>=0} 1/a(n) = (exp(1/4)+1)/2. - Amiram Eldar, Feb 02 2023
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MATHEMATICA
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With[{nn=20}, CoefficientList[Series[(1+4x)/(1-4x), {x, 0, nn}], x] Range[0, nn]!] (* or *) Join[{1}, Table[2*4^n n!, {n, 20}]] (* Harvey P. Dale, Jan 16 2012 *)
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PROG
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(PARI) for(n=0, 30, print1(if(n==0, 1, 2^(2*n+1)*n!), ", ")) \\ G. C. Greubel, Jan 17 2018
(Magma) [1] cat [2^(2*n+1)*Factorial(n): n in [2..30]]; // G. C. Greubel, Jan 17 2018
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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