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A001151 Describe the previous term! (method A - initial term is 8). 17

%I

%S 8,18,1118,3118,132118,1113122118,311311222118,13211321322118,

%T 1113122113121113222118,31131122211311123113322118,

%U 132113213221133112132123222118

%N Describe the previous term! (method A - initial term is 8).

%C Method A = 'frequency' followed by 'digit'-indication.

%C a(n+1) - a(n) is divisible by 10^5 for n > 5. - _Altug Alkan_, Dec 04 2015

%D S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 452-455.

%D I. Vardi, Computational Recreations in Mathematica. Addison-Wesley, Redwood City, CA, 1991, p. 4.

%H T. D. Noe, <a href="/A001151/b001151.txt">Table of n, a(n) for n=1..20</a>

%H J. H. Conway, <a href="http://dx.doi.org/10.1007/978-1-4612-4808-8_53">The weird and wonderful chemistry of audioactive decay</a>, in T. M. Cover and Gopinath, eds., Open Problems in Communication and Computation, Springer, NY 1987, pp. 173-188.

%H S. R. Finch, <a href="http://www.people.fas.harvard.edu/~sfinch/constant/cnwy/cnwy.html">Conway's Constant</a> [Broken link]

%e E.g. the term after 3118 is obtained by saying "one 3, two 1's, one 8", which gives 132118.

%t RunLengthEncode[x_List] := (Through[{First, Length}[ #1]] &) /@ Split[x]; LookAndSay[n_, d_: 1] := NestList[Flatten[Reverse /@ RunLengthEncode[ # ]] &, {d}, n - 1]; F[n_] := LookAndSay[n, 8][[n]]; Table[FromDigits[F[n]], {n, 1, 11}] (* _Zerinvary Lajos_, Jul 08 2009 *)

%Y Cf. A001155, A005150, A006751, A006715, A001140, A001141, A001143, A001145, A001154.

%K nonn,base,easy,nice

%O 1,1

%A _N. J. A. Sloane_

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Last modified October 15 21:06 EDT 2018. Contains 316237 sequences. (Running on oeis4.)