  We establish a recursive relation for the bipartition number $p_2(n)$ which
might be regarded as an analogue of Euler's recursive relation for the
partition number $p(n)$. Two proofs of the main result are proved in this
article. The first one is using the generating function, and the second one is
using combinatoric objects (called ``symbols'') created by Lusztig for studying
representation theory of finite classical groups.
