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

 

Logo

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A006715 Describe the previous term! (method A - initial term is 3).
(Formerly M2965)
25
3, 13, 1113, 3113, 132113, 1113122113, 311311222113, 13211321322113, 1113122113121113222113, 31131122211311123113322113, 132113213221133112132123222113, 11131221131211132221232112111312111213322113, 31131122211311123113321112131221123113111231121123222113 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

REFERENCES

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

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

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

Eric W. Weisstein, MathWorld: Look and Say Sequence.

EXAMPLE

The term after 3113 is obtained by saying "one 3, two 1's, one 3", which gives 132113.

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

PROG

(Perl)

# This outputs the first n elements of the sequence, where n is given on the command line.

$s = 3;

for (2..shift @ARGV) {

    print "$s, ";

    $s =~ s/(.)\1*/(length $&).$1/eg;

}

print "$s\n";

## Arne 'Timwi' Heizmann (timwi(AT)gmx.net), Mar 12 2008)

CROSSREFS

Cf. A001155, A005150, A006751, A001140, A001141, A001143, A001145, A001151, A001154.

Cf. A088204 (continuous version).

Sequence in context: A073428 A118628 A112513 * A177362 A138487 A022507

Adjacent sequences:  A006712 A006713 A006714 * A006716 A006717 A006718

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 | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified November 24 15:00 EST 2014. Contains 249899 sequences.