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A052695
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E.g.f. (2-5x)/((1-4x)(1-x)).
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0
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2, 5, 34, 390, 6168, 123000, 2949840, 82580400, 2642451840, 95127177600, 3805076217600, 167423233824000, 8036313786547200, 417888298219392000, 23401744438751078400, 1404104662402041600000, 89862698330962292736000
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history;
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OFFSET
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0,1
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LINKS
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Table of n, a(n) for n=0..16.
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 644
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FORMULA
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E.g.f.: -(-2+5*x)/(-1+4*x)/(-1+x)
Recurrence: {a(1)=5, a(0)=2, (4*n^2+12*n+8)*a(n)+(-10-5*n)*a(n+1)+a(n+2)=0}
(4^n+1)*n!
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MAPLE
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spec := [S, {S=Union(Sequence(Z), Sequence(Union(Z, Z, Z, Z)))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Sequence in context: A208985 A114793 A027303 * A184360 A206830 A002665
Adjacent sequences: A052692 A052693 A052694 * A052696 A052697 A052698
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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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