A376011 a(n) = number of solutions (x_1, x_2, ..., x_n) to Product_{i=1..n} (1 + 1/x_i) = 3.

0, 1, 3, 19, 276, 10341, 1526969

Offset: 1

Author

Keith F. Lynch, Sep 05 2024

Keywords

• hard
• nonn
• more

Comments

Number of ways 3 is a product of n superparticular ratios, without regard to order. A superparticular ratio is a ratio of the form (m+1)/m.

Examples

			a(3) = 3 since 3 can be written as (2/1)(4/3)(9/8), (2/1)(5/4)(6/5), or (3/2)^2 (4/3) but in no other way using superparticular ratios.
		

Crossrefs

Cf. A085098, A118086, A277608.