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Search: id:A052538
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| A052538 |
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A simple regular expression. |
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+0
1
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| 1, 1, 5, 10, 32, 79, 224, 589, 1613, 4321, 11714, 31552, 85283, 230080, 621353, 1677097, 4528013, 12223258, 32999264, 89084263, 240496544, 649248085, 1752733013, 4731720649, 12773896082, 34484755072, 93096036443
(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 469
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FORMULA
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G.f.: -(-1+x)/(1-2*x-3*x^2+3*x^3)
Recurrence: {a(1)=1, a(0)=1, a(2)=5, 3*a(n)-3*a(n+1)-2*a(n+2)+a(n+3)}
Sum(-1/107*(-13-38*_alpha+33*_alpha^2)*_alpha^(-1-n), _alpha=RootOf(1-2*_Z-3*_Z^2+3*_Z^3))
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MAPLE
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spec := [S, {S=Sequence(Prod(Z, Union(Z, Z, Z, Sequence(Z))))}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Sequence in context: A020995 A005201 A094234 this_sequence A073705 A121158 A032772
Adjacent sequences: A052535 A052536 A052537 this_sequence A052539 A052540 A052541
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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 08 2000
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