Erdős Number

As per Wikipedia, the Erdős number describes the collaborative distance between mathematician Paul Erdős and another person, as measured by authorship of mathematical papers.

As per this portal by the American Mathematical Sciety, my Erdős number is 4:

Umang Mathur	Shankara Narayanan Krishna	Weak Singular Hybrid Automata
Shankara Narayanan Krishna	Marian Gheorghe	On Restricted Bio-Turing Machines
Marian Gheorghe	Solomon Marcus	Special Issue Natural Computing: Theory and Applications
Solomon Marcus	Paul Erdős	Sur la décomposition de l'espace euclidien en ensembles homogènes