

A023989


Look and Say sequence: describe the previous term! (method C  initial term is 2).


6



2, 12, 1112, 3112, 211213, 312213, 212223, 114213, 31121314, 41122314, 31221324, 21322314, 21322314, 21322314, 21322314, 21322314, 21322314, 21322314, 21322314, 21322314, 21322314, 21322314, 21322314, 21322314, 21322314, 21322314, 21322314
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OFFSET

0,1


COMMENTS

Method C = 'frequency' followed by 'digit'indication with digits in increasing order.
Converges to 21322314 at the eleventh term. Depending on the initial value, the sequence may converge to a cycle of 2 or more values, for example : 123456, 111213141516, 711213141516, 611213141516, 611213141526, 512213141526, 413213142516, 412223241516, 314213241516, 412223241516, 314213241516, 412223241516
a(n) = A005151(n) for n > 6.  Reinhard Zumkeller, Jan 26 2014


LINKS

Table of n, a(n) for n=0..26.


EXAMPLE

a(1) = 12, so a(2) = 1112 because 12 contains a digit 1 and a digit 2; a(3) = 3112 because 1112 contains three digits 1 and a digit 2


PROG

(Haskell)
import Data.List (group, sort, transpose)
a023989 n = a023989_list !! (n1)
a023989_list = 2 : f [2] :: [Integer] where
f xs = (read $ concatMap show ys) : f (ys) where
ys = concat $ transpose [map length zss, map head zss]
zss = group $ sort xs
 Reinhard Zumkeller, Jan 26 2014


CROSSREFS

Cf. A005150, A022481.
Cf. A045918, A118628.
Sequence in context: A057120 A112512 A006751 * A001389 A022914 A177361
Adjacent sequences: A023986 A023987 A023988 * A023990 A023991 A023992


KEYWORD

nonn,base


AUTHOR

Artemario Tadeu Medeiros da Silva (artemario(AT)uol.com.br), Mar 19 2002


STATUS

approved



