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Search: id:A052546
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| A052546 |
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A simple regular expression. |
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+0
1
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| 1, 0, 1, 3, 2, 7, 13, 18, 41, 71, 122, 239, 421, 762, 1417, 2543, 4642, 8495, 15389, 28082, 51177, 93047, 169610, 308847, 562197, 1024170, 1864841, 3395711, 6184498, 11261551, 20507789, 37346914, 68008809, 123848199, 225535258
(list; graph; listen)
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OFFSET
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0,4
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 482
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FORMULA
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G.f.: -(-1+x)/(1-x-2*x^3+2*x^4-x^2)
Recurrence: {a(1)=0, a(0)=1, a(2)=1, a(3)=3, 2*a(n)-2*a(n+1)-a(n+2)-a(n+3)+a(n+4)}
Sum(-1/353*(-18-106*_alpha+33*_alpha^2+28*_alpha^3)*_alpha^(-1-n), _alpha=RootOf(1-_Z-2*_Z^3+2*_Z^4-_Z^2))
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MAPLE
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spec := [S, {S=Sequence(Prod(Z, Z, Union(Z, Z, Sequence(Z))))}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Adjacent sequences: A052543 A052544 A052545 this_sequence A052547 A052548 A052549
Sequence in context: A099329 A053440 A114647 this_sequence A049968 A049970 A104528
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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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