A063066 - OEIS

%I #4 May 29 2017 09:06:12

%S 9,24,45,64,72,105,120,144,189,192,225,240,280,297,360,384,429,504,

%T 525,576,585,640,672,720,765,792,840,864,945,960,969,1080,1144,1152,

%U 1197,1200,1225,1320,1344,1449,1485,1512,1560,1584,1680,1725,1792,1800,1872

%N Numbers expressible as (a^2-1)(b^2-1).

%H K. S. Brown, <a href="http://www.mathpages.com/home/kmath275.htm">Numbers Expressible as (a^2-1)(b^2-1)</a>

%e 45 is on the list because 45=(2^2-1)(4^2-1)

%t With[{nn=50},Take[(#[[1]]^2-1)(#[[2]]^2-1)&/@Tuples[Range[2,nn],2]//Union,nn]] (* _Harvey P. Dale_, May 29 2017 *)

%Y Cf. A057535, A063067, A063068.

%K nonn

%O 1,1

%A _Henry Bottomley_, Jul 08 2001