A262277 -id:A262277 - cp's OEIS frontend

A111708 a(n) = n concatenated with 9's complement of n.

9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 1089, 1188, 1287, 1386, 1485, 1584, 1683, 1782, 1881, 1980, 2079, 2178, 2277, 2376, 2475, 2574, 2673, 2772, 2871, 2970, 3069, 3168, 3267, 3366, 3465, 3564, 3663, 3762, 3861, 3960, 4059, 4158, 4257, 4356, 4455, 4554

Offset: 0

Amarnath Murthy, Aug 22 2005

If n has k digits a(n) is a multiple of 10^k -1.
The sequence contains 10^(k) multiples of 10^k -1.
a(n)/{10^k -1} gives all natural numbers.
All terms are multiples of 9: A007953(a(n))=9*A055642(n); A010888(a(n))=9. - Reinhard Zumkeller, Sep 17 2015

			a(90) = 9009.

Reinhard Zumkeller, Table of n, a(n) for n = 0..9999

Cf. A061601, A010888, A007953, A055642, subsequence of A262277.

a111708 0 = 9
a111708 n = f [] n where
   f ys 0 = foldl (\v d -> 10 * v + d) 0 $ ys ++ map (9 -) ys
   f ys x = f (d : ys) x' where (x', d) = divMod x 10
-- Reinhard Zumkeller, Sep 17 2015

More terms from Joshua Zucker, May 08 2006

Definition cleared and offset changed by Reinhard Zumkeller, Sep 17 2015

cp's OEIS Frontend

A111708 a(n) = n concatenated with 9's complement of n.

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