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Search: id:A081909
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| 1, 3, 10, 36, 135, 513, 1944, 7290, 26973, 98415, 354294, 1259712, 4428675, 15411789, 53144100, 181752822, 617003001, 2080591515, 6973568802, 23245229340, 77096677311, 254535261273, 836828256240, 2740612539186
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OFFSET
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0,2
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COMMENT
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Binomial transform of A081908. 3rd binomial transform of (1,0,1,0,0,0,......). Case k=3 where a(n,k)=k^n(n^2-n+2k^2)/(2k^2) with G.f. (1-2kx+(k^2+1)x^2)/(1-kx)^3
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FORMULA
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a(n)=3^n(n^2-n+18)/18 G.f.: (1-6x+10x^2)/(1-3x)^3
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CROSSREFS
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Cf. A081910.
Sequence in context: A102871 A119374 A126188 this_sequence A126189 A122448 A007582
Adjacent sequences: A081906 A081907 A081908 this_sequence A081910 A081911 A081912
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Mar 31 2003
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