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Search: id:A052977
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| A052977 |
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A simple regular expression. |
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+0
1
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| 1, 1, 1, 3, 5, 8, 15, 27, 47, 84, 150, 266, 473, 842, 1497, 2662, 4735, 8421, 14976, 26635, 47370, 84246, 149830, 266470, 473911, 842841, 1498976, 2665898, 4741245, 8432208, 14996510, 26670987, 47433807, 84360059, 150032645, 266830001
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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Equals INVERT transform of (1, 0, 2, 0, 1, 0, 1,...). [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Apr 28 2009]
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 1049
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FORMULA
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G.f.: -(-1+x^2)/(1-x^3-x-x^2+x^5)
Recurrence: {a(1)=1, a(0)=1, a(2)=1, a(3)=3, a(4)=5, a(n)-a(n+2)-a(n+3)-a(n+4)+a(n+5)}
Sum(-1/7031*(-798-714*_alpha^2-1887*_alpha+410*_alpha^4+986*_alpha^3)*_alpha^(-1-n), _alpha=RootOf(1-_Z^3-_Z-_Z^2+_Z^5))
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MAPLE
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spec := [S, {S=Sequence(Prod(Union(Sequence(Prod(Z, Z)), Prod(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: A080999 A077579 A076797 this_sequence A099846 A141775 A056765
Adjacent sequences: A052974 A052975 A052976 this_sequence A052978 A052979 A052980
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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 06 2000
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