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Search: id:A052903
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| A052903 |
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A simple regular expression. |
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+0
1
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| 1, 2, 4, 8, 17, 36, 76, 161, 341, 722, 1529, 3238, 6857, 14521, 30751, 65121, 137906, 292042, 618454, 1309693, 2773522, 5873456, 12438151, 26340131, 55780196, 118125087, 250152154, 529744373, 1121833637, 2375694341, 5030980901
(list; graph; listen)
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OFFSET
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0,2
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 881
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FORMULA
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G.f.: -(-1+x^3)/(1-2*x-x^3+x^4)
Recurrence: {a(0)=1, a(2)=4, a(1)=2, a(3)=8, a(n)-a(n+1)-2*a(n+3)+a(n+4)}
Sum(-1/643*(-222-40*_alpha-93*_alpha^2+54*_alpha^3)*_alpha^(-1-n), _alpha=RootOf(1-2*_Z-_Z^3+_Z^4))
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MAPLE
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spec := [S, {S=Sequence(Union(Z, Prod(Sequence(Prod(Z, Z, Z)), Z)))}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Sequence in context: A097107 A098083 A008999 this_sequence A063457 A157904 A002845
Adjacent sequences: A052900 A052901 A052902 this_sequence A052904 A052905 A052906
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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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EXTENSIONS
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More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jun 05 2000
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