A140134 a(n)=2a(n-1) but when sum of digits of 2a(n-1) is greater than 9 take a(n) = largest number < 2a(n-1) which has sum of digits = 9.

1, 2, 4, 8, 16, 32, 63, 126, 252, 504, 1008, 2016, 4032, 8001, 16002, 32004, 63000, 126000, 252000, 504000, 1008000, 2016000, 4032000, 8001000, 16002000, 32004000, 63000000, 126000000, 252000000, 504000000, 1008000000, 2016000000

Offset: 0

Author

Paul Curtz, Jun 15 2008

Keywords

• nonn
• base

Examples

			a(12)=4032; 2*4032 = 8064; digit sum is 18; decrease until we get a number with digit sum 9, which is 8001; so a(13) = 8001. - From _N. J. A. Sloane_, Oct 08 2012
		

Crossrefs

Cf. A062259.

Extensions

Keyword base added by Reinhard Zumkeller, Feb 25 2010