A134857 Numbers that can be written as (a^2-1)(b^2-1) in four or more distinct ways.

241920, 1048320, 10200960, 25724160, 37255680, 93139200, 123963840, 245044800, 588107520, 819786240, 1407893760, 1871251200, 3758169600, 5886558720, 8553283200, 10783342080, 13470367680, 19769460480, 30791819520, 40446806400

Offset

1,1

Comments

Subsequence of A134856. Contains A134858 as a subsequence.

Links

Table of n, a(n) for n=1..20.

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

Example

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. A134856, A134858.

Cf. A057535, A063066, A063067, A063068.

Sequence in context: A249194 A281887 A127881 * A251007 A078871 A249209

Adjacent sequences: A134854 A134855 A134856 * A134858 A134859 A134860

Keyword

easy,nonn

Author

Herman Beeksma, Nov 13 2007

Status

approved