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Search: id:A001140
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| A001140 |
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Describe the previous term! (method A - initial term is 4). |
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+0
11
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| 4, 14, 1114, 3114, 132114, 1113122114, 311311222114, 13211321322114, 1113122113121113222114, 31131122211311123113322114, 132113213221133112132123222114
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Method A = 'frequency' followed by 'digit'-indication.
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REFERENCES
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J. H. Conway, The weird and wonderful chemistry of audioactive decay, in T. M. Cover and Gopinath, eds., Open Problems in Communication and Computation, Springer, NY 1987, pp. 173-188.
S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 452-455.
I. Vardi, Computational Recreations in Mathematica. Addison-Wesley, Redwood City, CA, 1991, p. 4.
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LINKS
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S. R. Finch, Conway's Constant
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EXAMPLE
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E.g. the term after 3114 is obtained by saying "one 3, two 1's, one 4", which gives 132114.
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MATHEMATICA
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RunLengthEncode[ x_List ] := (Through[ {First, Length}[ #1 ] ] &) /@ Split[ x ]; LookAndSay[ n_, d_:1 ] := NestList[ Flatten[ Reverse /@ RunLengthEncode[ # ] ] &, {d}, n - 1 ]; F[ n_ ] := LookAndSay[ n, 4 ][ [ n ] ]; Table[ FromDigits[ F[ n ] ], {n, 1, 11} ] - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 21 2007
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CROSSREFS
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Cf. A001155, A005150, A006751, A006715, A001141, A001143, A001145, A001151, A001154.
Sequence in context: A003010 A118770 A112514 this_sequence A138488 A022508 A161741
Adjacent sequences: A001137 A001138 A001139 this_sequence A001141 A001142 A001143
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KEYWORD
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nonn,base,easy,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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