login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A001151 Describe the previous term! (method A - initial term is 8). 17
8, 18, 1118, 3118, 132118, 1113122118, 311311222118, 13211321322118, 1113122113121113222118, 31131122211311123113322118, 132113213221133112132123222118 (list; graph; refs; listen; history; text; internal format)
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. 452-455.

I. Vardi, Computational Recreations in Mathematica. Addison-Wesley, 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. 173-188.

S. R. Finch, Conway's Constant [Broken link]

EXAMPLE

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

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, 8][[n]]; Table[FromDigits[F[n]], {n, 1, 11}] (* Zerinvary Lajos, Jul 08 2009 *)

CROSSREFS

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

Sequence in context: A215174 A171371 A092692 * A177367 A138492 A022512

Adjacent sequences:  A001148 A001149 A001150 * A001152 A001153 A001154

KEYWORD

nonn,base,easy,nice

AUTHOR

N. J. A. Sloane

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified March 28 19:06 EDT 2017. Contains 284246 sequences.