A068861 a(1) = 1; a(n+1) is the smallest number not already in the sequence which differs from a(n) at every digit.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 21, 12, 20, 11, 22, 13, 24, 15, 23, 14, 25, 16, 27, 18, 26, 17, 28, 19, 30, 29, 31, 40, 32, 41, 33, 42, 34, 43, 35, 44, 36, 45, 37, 46, 38, 47, 39, 48, 50, 49, 51, 60, 52, 61, 53, 62, 54, 63, 55, 64, 56, 65, 57, 66, 58, 67, 59, 68, 70, 69, 71, 80

Offset: 1

Author

Amarnath Murthy, Mar 13 2002

Keywords

• nonn
• base

Examples

			11 follows 20 as the smallest number not included earlier and differing at every digit position.
		

Links

• Paul Tek, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A068860, A068863.

Cf. A067581.

Programs

Haskell

import Data.List (delete)
a068861 n = a068861_list !! (n-1)
a068861_list = f "x" (map show [1..]) where
   f u us = g us where
     g (v:vs)
       | and $ zipWith (/=) u v = (read v :: Int) : f v (delete v us)
       | otherwise = g vs
-- Reinhard Zumkeller, Dec 21 2013