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Search: id:A006751
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| A006751 |
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Describe the previous term! (method A - initial term is 2).
(Formerly M2052)
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+0
23
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| 2, 12, 1112, 3112, 132112, 1113122112, 311311222112, 13211321322112, 1113122113121113222112, 31131122211311123113322112, 132113213221133112132123222112
(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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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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EXAMPLE
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E.g. the term after 3112 is obtained by saying "one 3, two 1's, one 2", which gives 132112.
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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, 2 ][ [ 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, A006715, A001140, A001141, A001143, A001145, A001151, A001154.
Adjacent sequences: A006748 A006749 A006750 this_sequence A006752 A006753 A006754
Sequence in context: A058975 A057120 A112512 this_sequence A023989 A001389 A022914
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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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