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Search: id:A052951
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| A052951 |
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A simple regular expression. |
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+0
4
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| 1, 5, 14, 36, 88, 208, 480, 1088, 2432, 5376, 11776, 25600, 55296, 118784, 253952, 540672, 1146880, 2424832, 5111808, 10747904, 22544384, 47185920, 98566144, 205520896, 427819008, 889192448, 1845493760, 3825205248, 7918845952
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Equals binomial transform of A042948 starting with "1": (1, 4, 5, 8, 9, 12, 13,...) = terms >0, == 0 or 1 mod 4. [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Feb 07 2009]
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 1021
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FORMULA
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G.f.: -(-x+2*x^2-1)/(-1+2*x)^2
Recurrence: {a(0)=1, 4*a(n)-4*a(n+1)+a(n+2), a(1)=5, a(2)=14}
2^n*n+2^n+2^(n-1).
a(n) = A118413(n+1,n-1) for n>2. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Apr 27 2006
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MAPLE
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spec := [S, {S=Prod(Union(Sequence(Union(Z, Z)), Z), Sequence(Union(Z, Z)))}, unlabeled ]: seq(combstruct[count ](spec, size=n), n=0..20);
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CROSSREFS
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A042948 [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Feb 07 2009]
Sequence in context: A027983 A142585 A097507 this_sequence A048745 A127980 A054486
Adjacent sequences: A052948 A052949 A052950 this_sequence A052952 A052953 A052954
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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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