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Search: id:A066810
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| A066810 |
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Expansion of x^2/((1-3*x)*(1-2*x)^2). |
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+0
6
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| 0, 0, 1, 7, 33, 131, 473, 1611, 5281, 16867, 52905, 163835, 502769, 1532883, 4651897, 14070379, 42456897, 127894979, 384799049, 1156756443, 3475250065, 10436235955, 31330727961, 94038321227, 282211432673, 846835624611
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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Binomial transform of A000295.
a(n) = A112626(n, 2). - Ross La Haye (rlahaye(AT)new.rr.com), Jan 11 2006
Let Q be a binary relation on the power set P(A) of a set A having n = |A| elements such that for all x,y of P(A), xQy if x is a proper subset of y and |y| - |x| > 1. Then a(n) = |Q|. - Ross La Haye (rlahaye(AT)new.rr.com), Jan 11 2008
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FORMULA
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a(n) = 3^n - 2^n - n*2^(n-1)
a(n) = A000244(n) - A001792(n). a(n) = Sum[C(n,k)2^(n-k),{k,2,n}]. - Ross La Haye (rlahaye(AT)new.rr.com), Apr 26 2006
Inverse binomial transform of A086443. - Ross La Haye (rlahaye(AT)new.rr.com), Apr 29 2006
Convolution of A000244 beginning [0,1,3,9,27,81...] and A001787. - Ross La Haye (rlahaye(AT)new.rr.com), Feb 15 2007
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CROSSREFS
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Sequence in context: A100855 A000605 A114014 this_sequence A034577 A089106 A054256
Adjacent sequences: A066807 A066808 A066809 this_sequence A066811 A066812 A066813
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KEYWORD
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nonn
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AUTHOR
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njas, Jan 25 2002
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EXTENSIONS
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Additional comments from Ross La Haye (rlahaye(AT)new.rr.com), Sep 27 2005
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