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URL: https://oeis.org/A022519

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A022519
Describe previous term from the right (method B - initial term is 8).
5
8, 81, 1181, 118112, 21128112, 211281211221, 112212211181211221, 1122122111811322112212, 21112212223112811322112212, 21112212223112812112312311221321
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 1181 is obtained by saying "1 once, 8 once, 1 twice", which gives 118112.
PROG
(Haskell)
import Data.List (group, transpose)
a022519 n = a022519_list !! n
a022519_list = 8 : f [8] :: [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
(Python)
from itertools import groupby
A022519_list = [8]
for _ in range(10):
A022519_list.append(int(''.join(str(k)+str(len(list(g))) for k, g in groupby(str(A022519_list[-1])[::-1])))) # Chai Wah Wu, Sep 01 2021
CROSSREFS
KEYWORD
nonn,base,easy,nice
EXTENSIONS
More terms from Patrick De Geest, Jun 15 1999
STATUS
approved