Search: id:A121808
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%I A121808
%S A121808 1,11,12,1121,1321,122131,132231,122232,112431,13213141,14213241,
%T A121808 13223142,12233241,12233241,12233241,12233241,12233241,12233241,
%U A121808 12233241,12233241,12233241,12233241
%N A121808 Say what you see in previous term, reporting each digit encountered followed 
               by frequency.
%F A121808 Constant at 12233241 after 13 terms.
%e A121808 To get the term after 13213141, we say: four 1's, one 2, two 3's, one 
               4; therefore 14213241 (digit named before frequency).
%t A121808 RunLengthEncode[ x_List ] := (Through[ {First, Length}[ #1 ] ] &) /@ 
               Split@ Sort@x; LookAndSay[ n_, d_:1 ] := NestList[ Flatten[ Reverse 
               /@ RunLengthEncode[ # ] ] &, {d}, n - 1 ]; F[ n_ ] := LookAndSay[ 
               n, 1 ][ [ n ] ]; Table[ FromDigits[ F[ n ] ], {n, 1, 15} ] (* Robert 
               G. Wilson v Sep 11 2006 *)
%Y A121808 Another variant of A005150, A005151, A063850, etc.
%Y A121808 Sequence in context: A056684 A042731 A087304 this_sequence A160265 A007651 
               A022481
%Y A121808 Adjacent sequences: A121805 A121806 A121807 this_sequence A121809 A121810 
               A121811
%K A121808 base,easy,nonn
%O A121808 1,2
%A A121808 Ross Presser (rpresser(AT)gmail.com), Sep 09 2006

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