Search: id:A001145
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%I A001145
%S A001145 7,17,1117,3117,132117,1113122117,311311222117,13211321322117,
%T A001145 1113122113121113222117,31131122211311123113322117,
%U A001145 132113213221133112132123222117
%N A001145 Describe the previous term! (method A - initial term is 7).
%C A001145 Method A = 'frequency' followed by 'digit'-indication.
%D A001145 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.
%D A001145 S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 452-455.
%D A001145 I. Vardi, Computational Recreations in Mathematica. Addison-Wesley, Redwood 
               City, CA, 1991, p. 4.
%H A001145 S. R. Finch, <a href="http://algo.inria.fr/bsolve/constant/cnwy/cnwy.html">
               Conway's Constant</a>
%e A001145 E.g. the term after 3117 is obtained by saying "one 3, two 1's, one 7", 
               which gives 132117.
%t A001145 RunLengthEncode[x_List] := (Through[{First, Length}[ #1]] &) /@ Split[x]; 
               LookAndSay[n_, d_: 1] := NestList[Flatten[Reverse /@ RunLengthEncode[ 
               # ]] &, {d}, n - 1]; F[n_] := LookAndSay[n, 7][[n]]; Table[FromDigits[F[n]], 
               {n, 1, 11}] [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Jul 08 2009]
%Y A001145 Cf. A001155, A005150, A006751, A006715, A001140, A001141, A001143, A001151, 
               A001154.
%Y A001145 Sequence in context: A102266 A113765 A153375 this_sequence A093139 A138491 
               A022511
%Y A001145 Adjacent sequences: A001142 A001143 A001144 this_sequence A001146 A001147 
               A001148
%K A001145 nonn,base,easy,nice
%O A001145 1,1
%A A001145 N. J. A. Sloane (njas(AT)research.att.com).

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