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%I #10 Sep 17 2015 14:22:24
%S 9,18,27,36,45,54,63,72,81,90,1089,1188,1287,1386,1485,1584,1683,1782,
%T 1881,1980,2079,2178,2277,2376,2475,2574,2673,2772,2871,2970,3069,
%U 3168,3267,3366,3465,3564,3663,3762,3861,3960,4059,4158,4257,4356,4455,4554
%N a(n) = n concatenated with 9's complement of n.
%C If n has k digits a(n) is a multiple of 10^k -1.
%C The sequence contains 10^(k) multiples of 10^k -1.
%C a(n)/{10^k -1} gives all natural numbers.
%C All terms are multiples of 9: A007953(a(n))=9*A055642(n); A010888(a(n))=9. - _Reinhard Zumkeller_, Sep 17 2015
%H Reinhard Zumkeller, <a href="/A111708/b111708.txt">Table of n, a(n) for n = 0..9999</a>
%e a(90) = 9009.
%o (Haskell)
%o a111708 0 = 9
%o a111708 n = f [] n where
%o f ys 0 = foldl (\v d -> 10 * v + d) 0 $ ys ++ map (9 -) ys
%o f ys x = f (d : ys) x' where (x', d) = divMod x 10
%o -- _Reinhard Zumkeller_, Sep 17 2015
%Y Cf. A061601, A010888, A007953, A055642, subsequence of A262277.
%K base,easy,nonn
%O 0,1
%A _Amarnath Murthy_, Aug 22 2005
%E More terms from _Joshua Zucker_, May 08 2006
%E Definition cleared and offset changed by _Reinhard Zumkeller_, Sep 17 2015
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