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A022514
Describe previous term from the right (method B - initial term is 3).
9
3, 31, 1131, 113112, 21123112, 211231211221, 112212211131211221, 1122122111311322112212, 21112212223112311322112212, 21112212223112312112312311221321
OFFSET
0,1
COMMENTS
Method B = 'digit'-indication followed by 'frequency'.
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 0..21
EXAMPLE
The term after 1131 is obtained by saying "1 once, 3 once, 1 twice", which gives 113112.
MATHEMATICA
A022514[1]:=3; A022514[n_]:=A022514[n]=FromDigits[Flatten[{First[#], Length[#]}&/@Split[Reverse[IntegerDigits[A022514[n-1]]]]]]; Map[A022514, Range[15]] (* Peter J. C. Moses, Apr 22 2013 *)
PROG
(Haskell)
import Data.List (group, transpose)
a022514 n = a022514_list !! n
a022514_list = 3 : f [3] :: [Integer] where
f xs = (read $ concatMap show ys) : f ys where
ys = concat $ transpose [map head zss, map length zss]
zss = reverse $ group xs
-- Reinhard Zumkeller, Jan 26 2014
CROSSREFS
KEYWORD
nonn,base,easy,nice
EXTENSIONS
More terms from Patrick De Geest, Jun 15 1999
STATUS
approved