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Search: id:A124720
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| A124720 |
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Number of ternary Lyndon words with exactly two 1's. |
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+0
6
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| 2, 5, 16, 38, 96, 220, 512, 1144, 2560, 5616, 12288, 26592, 57344, 122816, 262144, 556928, 1179648, 2490112, 5242880, 11009536, 23068672, 48233472, 100663296, 209713152, 436207616, 905965568, 1879048192, 3892305920, 8053063680
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OFFSET
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3,1
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COMMENT
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If the offsets are modified, A124720 to A124723 are the 2nd to 5th Witt transform of A000079 [Moree]. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 08 2008]
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LINKS
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Pieter Moree, The formal series Witt transform, Discr. Math. no. 295 vol. 1-3 (2005) 143-160. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 08 2008]
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FORMULA
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G.f.: x^3*(2-3 x)/((1-2 x^2)(1- 2x)^2) = (x^2/(1-2x)^2 - x^2/(1-2*x^2))/2
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EXAMPLE
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a(4) = 5 because 1122, 1123, 1132, 1213, 1133 are all Lyndon words on 3 letters with 2 ones.
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CROSSREFS
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Cf. A051168, A027376, A124721, A124722, A124723.
Sequence in context: A053683 A082085 A054971 this_sequence A076958 A163825 A102866
Adjacent sequences: A124717 A124718 A124719 this_sequence A124721 A124722 A124723
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KEYWORD
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nonn
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AUTHOR
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Mike Zabrocki (zabrocki(AT)mathstat.yorku.ca), Nov 05 2006
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