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A009994
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Numbers with digits in nondecreasing order.
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11
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 22, 23, 24, 25, 26, 27, 28, 29, 33, 34, 35, 36, 37, 38, 39, 44, 45, 46, 47, 48, 49, 55, 56, 57, 58, 59, 66, 67, 68, 69, 77, 78, 79, 88, 89, 99, 111, 112, 113, 114, 115, 116, 117, 118, 119, 122
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,3
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COMMENTS
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Record values and occurrences of A004185. [From Reinhard Zumkeller, Dec 05 2009]
Although lists normally have offset 1, it seems appropriate to make an exception for this sequence. - N. J. A. Sloane, Jul 05 2010
A193581(a(n)) = 0. [Reinhard Zumkeller, Aug 10 2011]
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REFERENCES
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Amarnath Murthy and Robert J. Clarke, Some Properties of Staircase sequence, Mathematics & Informatics Quarterly, Volume 11, No. 4, November 2001.
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LINKS
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R. Zumkeller, Table of n, a(n) for n = 0..1000 [From Reinhard Zumkeller, Dec 05 2009]
Eric Weisstein's World of Mathematics, Digit.
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MATHEMATICA
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Select[Range[0, 125], LessEqual@@IntegerDigits[#]&] (* Ray Chandler, Oct 25 2011 *)
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PROG
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(Haskell)
import Data.Set (fromList, deleteFindMin, insert)
a009994 n = a009994_list !! n
a009994_list = 0 : f (fromList [1..9]) where
f s = m : f (foldl (flip insert) s' $ map (10*m +) [m `mod` 10 ..9])
where (m, s') = deleteFindMin s
-- Reinhard Zumkeller, Aug 10 2011
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CROSSREFS
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Cf. A152054.
Cf. A036839.
Sequence in context: A131058 A032857 A072544 * A102827 A190221 A055571
Adjacent sequences: A009991 A009992 A009993 * A009995 A009996 A009997
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KEYWORD
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nonn,base
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AUTHOR
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N. J. A. Sloane.
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EXTENSIONS
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Minor edits by Ray Chandler, Oct 25 2011
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STATUS
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approved
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