Tunnell's theorem states that supposing n is a congruent number, if n is odd then 2An = Bn and if n is even then 2Cn = Dn.
Tunnell's theorem states that for a congruent number 'n', if 'n' is odd, then 2 * An = Bn; and if 'n' is even, then 2 * Cn = Dn.