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Search: id:A052929
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| A052929 |
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A simple regular expression. |
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+0
1
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| 2, 3, 10, 27, 82, 243, 730, 2187, 6562, 19683, 59050, 177147, 531442, 1594323, 4782970, 14348907, 43046722, 129140163, 387420490, 1162261467, 3486784402, 10460353203, 31381059610, 94143178827, 282429536482, 847288609443
(list; graph; listen)
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OFFSET
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0,1
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 915
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FORMULA
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G.f.: -(-2+3*x+x^2)/(-1+x^2)/(-1+3*x)
Recurrence: {a(1)=3, a(2)=10, a(0)=2, -3*a(n)-2*a(n+1)+a(n+2)+2}
3^n+Sum(1/2*_alpha^(-n), _alpha=RootOf(-1+_Z^2))
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MAPLE
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spec := [S, {S=Union(Sequence(Prod(Z, Z)), Sequence(Union(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: A103018 A005158 A005225 this_sequence A151415 A134588 A000060
Adjacent sequences: A052926 A052927 A052928 this_sequence A052930 A052931 A052932
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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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