Ideals with polynomially increasing Groebner bases

Hi there,

how do I get a sequence of ideals with polynomially increasing Groebner
bases (wrt. some standard monomial ordering).

A little more formally, is there a recipe that, given a number N,
produces a non-trivial ideal in Q[x1,x2,x3] with a Groebner basis of
size greater than N, but bounded by p(N) where p is a polynomial? Q
stands for the rationals. (The number of variables is fixed)

What happens if more variables are considered?

Stephan

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