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Search: id:A052933
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| A052933 |
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A simple regular expression. |
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+0
1
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| 1, 1, 3, 6, 13, 29, 62, 137, 297, 650, 1417, 3093, 6750, 14729, 32145, 70146, 153081, 334061, 729014, 1590905, 3471785, 7576378, 16533705, 36081029, 78738574, 171828905, 374977217, 818301874, 1785756377, 3897004189, 8504318886
(list; graph; listen)
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OFFSET
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0,3
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 920
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FORMULA
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G.f.: -(-1+x^2)/(1-3*x^2+2*x^4-x)
Recurrence: {a(1)=1, a(0)=1, a(3)=6, a(2)=3, 2*a(n)-3*a(n+2)-a(n+3)+a(n+4)}
Sum(-1/397*(-148*_alpha+27*_alpha^2+82*_alpha^3-51)*_alpha^(-1-n), _alpha=RootOf(1-3*_Z^2+2*_Z^4-_Z))
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MAPLE
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spec := [S, {S=Sequence(Prod(Z, Union(Z, Z, Sequence(Prod(Z, Z)))))}, unlabeled ]: seq(combstruct[count ](spec, size=n), n=0..20);
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CROSSREFS
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Adjacent sequences: A052930 A052931 A052932 this_sequence A052934 A052935 A052936
Sequence in context: A095768 A002478 A106496 this_sequence A071014 A078061 A018909
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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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