

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
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OFFSET

1,1


COMMENTS

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


REFERENCES

S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 452455.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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
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



