  We focus on a family of equalities pioneered by Zhang and generalized by Zao
and Wang and hence by Mansour which involves self convolution of generalized
Fibonacci numbers. We show that all these formulas are nicely stated in only
one equation involving a bivariate ordinary generating function and we give
also a formula for the coefficients appearing in that context. As a
consequence, we give the general forms for the equalities of Zhang, Zao-Wang
and Mansour.
