A134858 Numbers that can be written as (a^2 - 1)(b^2 - 1) in five or more distinct ways.

588107520, 67270694400, 546939993600, 2128050512640, 37400697734400, 5566067918611200

Offset: 1

Author

Herman Beeksma, Nov 13 2007

Keywords

• hard
• more
• nonn

Comments

Subsequence of A134856 and A134857.

Depending on the interpretation of A057535, this is either the same or a supersequence of A057535. [R. J. Mathar, Oct 16 2009]

The next term (if it exists) is greater than 2^70.

Examples

			588107520 = (13^2 - 1)(1871^2 - 1) = (17^2 - 1)(1429^2 - 1) = (55^2 - 1)(441^2 - 1) = (79^2 - 1)(307^2 - 1) = (129^2 - 1)(188^2 - 1).
		

Links

• MathPages, Numbers Expressible As (a^2-1)(b^2-1).

Crossrefs

Cf. A057535, A134857, A134856, A063067, A063066, A063068.