A022514 Describe previous term from the right (method B - initial term is 3).

3, 31, 1131, 113112, 21123112, 211231211221, 112212211131211221, 1122122111311322112212, 21112212223112311322112212, 21112212223112312112312311221321

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• base
• easy
• nice

Comments

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

Examples

			The term after 1131 is obtained by saying "1 once, 3 once, 1 twice", which gives 113112.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..21

Crossrefs

Cf. A022481, A022488, A022515-A022520.

Programs

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

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 *)

Extensions

More terms from Patrick De Geest, Jun 15 1999