

A001141


Describe the previous term! (method A  initial term is 5).


15



5, 15, 1115, 3115, 132115, 1113122115, 311311222115, 13211321322115, 1113122113121113222115, 31131122211311123113322115, 132113213221133112132123222115
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OFFSET

1,1


COMMENTS

Method A = 'frequency' followed by 'digit'indication.
A001155, A001140, A001141, A001143, A001145, A001151 and A001154 are all identical apart from the last digit of each term (the seed). This is because digits other than 1, 2 and 3 never arise elsewhere in the terms (other than at the end of each of them) of lookandsay sequences of this type (as is mentioned by Carmine Suriano in A006751).  Chayim Lowen, Jul 16 2015
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

The term after 3115 is obtained by saying "one 3, two 1's, one 5", which gives 132115.


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, 5 ][ [ n ] ]; Table[ FromDigits[ F[ n ] ], {n, 1, 11} ] (* Zerinvary Lajos, Mar 21 2007 *)


CROSSREFS

Cf. A001155, A005150, A006751, A006715, A001140, A001143, A001145, A001151, A001154.
Sequence in context: A247882 A215901 A112515 * A177364 A138489 A022509
Adjacent sequences: A001138 A001139 A001140 * A001142 A001143 A001144


KEYWORD

nonn,base,easy,nice


AUTHOR

N. J. A. Sloane


STATUS

approved



