A216601 Number of ways to write n as a product with all factors <= n/5.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 2, 1, 0, 1, 0, 0, 2, 0, 3, 0, 0, 1, 4, 0, 0, 0, 3, 0, 2, 0, 0, 2, 0, 0, 7, 1, 2, 0, 0, 0, 4, 1, 3, 0, 0, 0, 6, 0, 0, 2, 7, 1, 2, 0, 0, 0, 3, 0, 11, 0, 0, 2, 0, 1, 2, 0, 8, 3, 0, 0, 6, 1, 0

Offset: 1

Author

Reinhard Zumkeller, Oct 01 2012

Keywords

• nonn

Comments

a(n) = A066032(n,floor(n/5)) for n > 4.

Examples

			a(50) = #{10*2, 5*5*2} = 2;
a(51) = #{} = 0;
a(52) = #{} = 0;
a(53) = #{} = 0;
a(54) = #{9*6, 9*3*2, 6*3*3, 3*3*3*2} = 4;
a(55) = #{11*5} = 1.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A001055, A028422, A216599, A216600, A216602.

Programs

Haskell

a216601 n | n <= 4    = 0
          | otherwise = a066032_tabl !! (n-1) !! (n `div` 5 - 1)