A228722 Largest number <= n with alternating parities of digits in decimal representation.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 12, 12, 14, 14, 16, 16, 18, 18, 18, 21, 21, 23, 23, 25, 25, 27, 27, 29, 30, 30, 32, 32, 34, 34, 36, 36, 38, 38, 38, 41, 41, 43, 43, 45, 45, 47, 47, 49, 50, 50, 52, 52, 54, 54, 56, 56, 58, 58, 58, 61, 61, 63, 63, 65, 65

Offset: 0

Author

Reinhard Zumkeller, Aug 31 2013

Keywords

• nonn
• base

Comments

a(n) <= n <= A228723(n) and A228710(a(n)) = 1;

a(A030141(n)) = A030141(n); a(A228709(n)) < A228709(n).

Examples

			a(100) = 98; a(1000) = 989; a(10000) = 9898; a(100000) = 98989;
a(101) = 101; a(1001) = 989.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Programs

Haskell

a228722 n = head [x | x <- [n, n-1 ..], a228710 x == 1]