A131470 a(n)=smallest number that gives a product with the sum of digits of n written in base 2 greater than n.

2, 3, 2, 5, 3, 4, 3, 9, 5, 6, 4, 7, 5, 5, 4, 17, 9, 10, 7, 11, 8, 8, 6, 13, 9, 9, 7, 10, 8, 8, 7, 33, 17, 18, 12, 19, 13, 13, 10, 21, 14, 15, 11, 15, 12, 12, 10, 25, 17, 17, 13, 18, 14, 14, 12, 19, 15, 15, 12, 16, 13, 13, 11, 65, 33, 34, 23

Offset: 1

Author

Philippe LALLOUET (philip.lallouet(AT)wanadoo.fr), Jul 27 2007

Keywords

• easy
• nonn
• base

Examples

			9 is written 1001 in base 2, then sd2(9)=2; 4*2<9<5*2; then (c,9)=5
		

Formula

Let sd2(n) the sum of digits of n written in base 2. Then a(n) =1 + Floor(n/sd2(n)).