A 2D graphical representation of DNA sequences using a two-quadrant cartesian coordinates system has been derived for mathematical denotation of DNA sequence. The 2D graphical representation also avoids loss of information accompanying alternative 2D and 3D representation in which the curve standing for DNA sequence overlaps and intersects itself, and resolves sequences' degeneracy. The geometrical centers of the two dimension graph of DNA sequences indicate the distribution of base frequencies with different parameter n and m. (C) 2004 Elsevier B.V. All rights reserved.