A063068 Smallest number expressible as (a^2-1)(b^2-1) in at least n distinct ways [with b>=a>1].

9, 360, 2880, 241920, 588107520

Offset

1,1

Comments

Note that each term is a multiple of the preceding term (at least up to a(5)).

Links

Table of n, a(n) for n=1..5.

K. S. Brown, Numbers Expressible as (a^2-1)(b^2-1)

K. S. Brown, MathPages Most Wanted List Problem #14

Example

a(4)=241920 since 241920 =(4^2-1)(127^2-1) =(7^2-1)(71^2-1) =(9^2-1)(55^2-1) =(17^2-1)(29^2-1)

Crossrefs

Cf. A057535, A063066, A063067.

Sequence in context: A266881 A119756 A222697 * A130558 A132593 A162133

Adjacent sequences: A063065 A063066 A063067 * A063069 A063070 A063071

Keyword

more,nonn

Author

Henry Bottomley, Jul 08 2001

Status

approved