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%I #11 Aug 30 2015 07:21:59
%S 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,
%T 28,19,30,29,31,40,32,41,33,42,34,43,35,44,36,45,37,46,38,47,39,48,50,
%U 49,51,60,52,61,53,62,54,63,55,64,56,65,57,66,58,67,59,68,70,69,71,80
%N a(1) = 1; a(n+1) is the smallest number not already in the sequence which differs from a(n) at every digit.
%H Paul Tek, <a href="/A068861/b068861.txt">Table of n, a(n) for n = 1..10000</a>
%e 11 follows 20 as the smallest number not included earlier and differing at every digit position.
%o (Haskell)
%o import Data.List (delete)
%o a068861 n = a068861_list !! (n-1)
%o a068861_list = f "x" (map show [1..]) where
%o f u us = g us where
%o g (v:vs)
%o | and $ zipWith (/=) u v = (read v :: Int) : f v (delete v us)
%o | otherwise = g vs
%o -- _Reinhard Zumkeller_, Dec 21 2013
%Y Cf. A068860, A068863.
%Y Cf. A067581.
%K nonn,base
%O 1,2
%A _Amarnath Murthy_, Mar 13 2002
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