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A009994 Numbers with digits in nondecreasing order. 16
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)
OFFSET

1,3

COMMENTS

Record values and occurrences of A004185. - Reinhard Zumkeller, Dec 05 2009

A193581(a(n)) = 0. - Reinhard Zumkeller, Aug 10 2011

REFERENCES

Amarnath Murthy and Robert J. Clarke, Some Properties of Staircase sequence, Mathematics & Informatics Quarterly, Volume 11, No. 4, November 2001.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Eric Weisstein's World of Mathematics, Digit.

FORMULA

a(n) >> exp(n^(1/10)). - Charles R Greathouse IV, Mar 15 2014

MATHEMATICA

Select[Range[0, 125], LessEqual@@IntegerDigits[#]&] (* Ray Chandler, Oct 25 2011 *)

PROG

(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

(PARI) is(n)=n=digits(n); n==vecsort(n) \\ Charles R Greathouse IV, Dec 03 2013

CROSSREFS

Cf. A152054, A036839.

Sequence in context: A131058 A032857 A072544 * A239016 A102827 A190221

Adjacent sequences:  A009991 A009992 A009993 * A009995 A009996 A009997

KEYWORD

nonn,base,look

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified April 21 01:47 EDT 2014. Contains 240824 sequences.