

A001145


Describe the previous term! (method A  initial term is 7).


15



7, 17, 1117, 3117, 132117, 1113122117, 311311222117, 13211321322117, 1113122113121113222117, 31131122211311123113322117, 132113213221133112132123222117
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OFFSET

1,1


COMMENTS

Method A = 'frequency' followed by 'digit'indication.
a(n+1)  a(n) is divisible by 10^5 for n > 5.  Altug Alkan, Dec 04 2015


REFERENCES

S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 452455.
I. Vardi, Computational Recreations in Mathematica. AddisonWesley, Redwood City, CA, 1991, p. 4.


LINKS

T. D. Noe, Table of n, a(n) for n=1..20
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. 173188.
S. R. Finch, Conway's Constant [Broken link]
S. R. Finch, Conway's Constant [From the Wayback Machine]


EXAMPLE

E.g. the term after 3117 is obtained by saying "one 3, two 1's, one 7", which gives 132117.


MATHEMATICA

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}] (* Zerinvary Lajos, Jul 08 2009 *)


CROSSREFS

Cf. A001155, A005150, A006751, A006715, A001140, A001141, A001143, A001151, A001154.
Sequence in context: A269447 A013540 A153375 * A093139 A177366 A138491
Adjacent sequences: A001142 A001143 A001144 * A001146 A001147 A001148


KEYWORD

nonn,base,easy,nice


AUTHOR

N. J. A. Sloane


STATUS

approved



