[seqfan] The two square composite sequence.

[DAN_CYN_J]

The two squares associated with each semi-prime composite. 

The rules for the simi-prime composite is no composite 
will be a 0(mod 3 or 5) 
Each of it's two factors will be of equal length or 1 digit 
less like 7*11 =77 is the first composite in the 3rd index of 
the sequence. The two previous index are just the two squares 
that is the solution to the composites two factors. 
So every third term is a composite and the two previous terms are 
it's associated squares as solutions. 
Which is the solution to x^2 - c = y^2 where c = a semi-prime composite 
and is known as the Fermat factoring method. 


The sequence begins -- 

4,81,77,9,100,91,25,144,119,36,169,133,1,144,143,64,225,161,9,196,187,121,324,203... 

Dan