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Search: id:A052938
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A052938 A simple regular expression. +0
7
1, 3, 2, 4, 3, 5, 4, 6, 5, 7, 6, 8, 7, 9, 8, 10, 9, 11, 10, 12, 11, 13, 12, 14, 13, 15, 14, 16, 15, 17, 16, 18, 17, 19, 18, 20, 19, 21, 20, 22, 21, 23, 22, 24, 23, 25, 24, 26, 25, 27, 26, 28, 27, 29, 28, 30, 29, 31, 30, 32, 31, 33, 32, 34, 33, 35, 34, 36, 35, 37, 36, 38, 37, 39 (list; graph; listen)
OFFSET

0,2

LINKS

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 929

FORMULA

G.f.: -(-2*x+2*x^2-1)/(-1+x)/(-1+x^2)

Recurrence: {a(0)=1, a(2)=2, a(1)=3, a(n)+a(n+1)-n-4}

3/4*(-1)^(1-n)+1/2*n+7/4

A112034(n) = 3*2^a(n); a(n) = A109613(n+2) - A084964(n). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 27 2005

a(n)=n-a(n-1)+2 (with a(1)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 21 2009]

EXAMPLE

For n=2, a(2)=2-1+2=3; n=3, a(3)=3-3+2=2; n=4, a(4)=4-2+2=4 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 21 2009]

MAPLE

spec := [S, {S=Prod(Union(Sequence(Z), Z, Z), Sequence(Prod(Z, Z)))}, unlabeled ]: seq(combstruct[count ](spec, size=n), n=0..20);

CROSSREFS

Cf. A028242 (same sequence with 1,0,2 prefix). [From Rick L. Shepherd (rshepherd2(AT)hotmail.com), Jul 16 2009]

Sequence in context: A134559 A007456 A119707 this_sequence A140114 A025532 A133131

Adjacent sequences: A052935 A052936 A052937 this_sequence A052939 A052940 A052941

KEYWORD

easy,nonn

AUTHOR

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

EXTENSIONS

More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jun 06 2000

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Last modified March 20 09:10 EDT 2010. Contains 173642 sequences.


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