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A022520
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Describe previous term from the right (method B - initial term is 9).
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9
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OFFSET
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0,1
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COMMENTS
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Method B = 'digit'-indication followed by 'frequency'.
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LINKS
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EXAMPLE
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The term after 1191 is obtained by saying "1 once, 9 once, 1 twice", which gives 119112.
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PROG
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(Haskell)
import Data.List (group, transpose)
a022520 n = a022520_list !! n
a022520_list = 9 : f [9] :: [Integer] where
f xs = (read $ concatMap show ys) : f ys where
ys = concat $ transpose [map head zss, map length zss]
zss = reverse $ group xs
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CROSSREFS
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KEYWORD
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nonn,base,easy,nice
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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