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 A121808 Say what you see in previous term, reporting each digit encountered followed by frequency. 1
 1, 11, 12, 1121, 1321, 122131, 132231, 122232, 112431, 13213141, 14213241, 13223142, 12233241, 12233241, 12233241, 12233241, 12233241, 12233241, 12233241, 12233241, 12233241, 12233241 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..22. FORMULA Constant at 12233241 after 13 terms. EXAMPLE To get the term after 13213141, we say: four 1's, one 2, two 3's, one 4; therefore 14213241 (digit named before frequency). MATHEMATICA 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 *) CROSSREFS Another variant of A005150, A005151, A063850, etc. Sequence in context: A042731 A087304 A340204 * A160265 A007651 A022481 Adjacent sequences: A121805 A121806 A121807 * A121809 A121810 A121811 KEYWORD base,easy,nonn AUTHOR Ross Presser (rpresser(AT)gmail.com), Sep 09 2006 STATUS approved

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Last modified February 25 19:26 EST 2024. Contains 370332 sequences. (Running on oeis4.)