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A052654
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E.g.f. 1/((1-x)(1-4x)).
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0
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1, 5, 42, 510, 8184, 163800, 3931920, 110098800, 3523201920, 126835632000, 5073428908800, 223230911904000, 10715084250393600, 557184387247488000, 31202325773037619200, 1872139547689931520000, 119816931073078407168000
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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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E.g.f.: 1/(-1+x)/(-1+4*x)
Recurrence: {a(0)=1, a(1)=5, (4*n^2+12*n+8)*a(n)+(-10-5*n)*a(n+1)+a(n+2)=0}
(-1/3+1/3*4^(n+1))*n!
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MAPLE
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spec := [S, {S=Prod(Sequence(Z), Sequence(Union(Z, Z, Z, Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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MATHEMATICA
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With[{nn=20}, CoefficientList[Series[1/((1-x)(1-4x)), {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Mar 13 2015 *)
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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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encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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STATUS
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approved
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