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A022507
Describe previous term from the right (method A - initial term is 3).
10
3, 13, 1311, 211311, 21132112, 122112132112, 122112131112212211, 2122112231131112212211, 21221122311321132221221112, 12312211321321121321132221221112
OFFSET
0,1
COMMENTS
Method A = 'frequency' followed by 'digit'-indication.
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 0..21
Eric Weisstein's World of Mathematics, Look and Say Sequence
FORMULA
a(n+1) = A045918(A004086(a(n))). - Reinhard Zumkeller, Mar 02 2014
EXAMPLE
The term after 1311 is obtained by saying "two 1's, one 3, one 1", which gives 211311.
MATHEMATICA
A022507[1]:=3; A022507[n_]:=A022507[n]=FromDigits[Flatten[{Length[#], First[#]}&/@Split[Reverse[IntegerDigits[A022507[n-1]]]]]]; Map[A022507, Range[15]] (* Peter J. C. Moses, Apr 22 2013 *)
PROG
(Haskell)
a022507 n = a022507_list !! n
a022507_list = iterate (a045918 . a004086) 3
-- Reinhard Zumkeller, Mar 02 2014
CROSSREFS
KEYWORD
nonn,base,easy,nice
EXTENSIONS
More terms from Erich Friedman
STATUS
approved