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Search: id:A052549
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| A052549 |
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A simple regular expression. |
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+0
8
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| 1, 4, 9, 19, 39, 79, 159, 319, 639, 1279, 2559, 5119, 10239, 20479, 40959, 81919, 163839, 327679, 655359, 1310719, 2621439, 5242879, 10485759, 20971519, 41943039, 83886079, 167772159, 335544319, 671088639, 1342177279, 2684354559
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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A153894 is a better version of this sequence. - N. J. A. Sloane (njas(AT)research.att.com), Feb 07 2009.
Equals binomial transform of [1, 3, 2, 3, 2, 3, 2,...] and row sums of triangle A140183. - Gary W. Adamson (qntmpkt(AT)yahoo.com), May 11 2008
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 486
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FORMULA
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G.f.: -(-x+x^2-1)/((-1+2*x)*(-1+x)).
Recurrence: {a(0)=1, -2*a(n)+a(n+1)-1, a(1)=4, a(2)=9}
Row sums of triangle A133601. - Gary W. Adamson (qntmpkt(AT)yahoo.com), Sep 18 2007
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MAPLE
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spec := [S, {S=Prod(Sequence(Union(Z, Z)), Union(Z, Sequence(Z)))}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);
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MATHEMATICA
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a=4; lst={1, a}; k=5; Do[a+=k; AppendTo[lst, a]; k+=k, {n, 0, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 15 2008]
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CROSSREFS
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Cf. A133601, A140183, A153894.
Sequence in context: A101353 A008135 A009885 this_sequence A153894 A034479 A023377
Adjacent sequences: A052546 A052547 A052548 this_sequence A052550 A052551 A052552
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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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