Wacaw Franciszek Sierpinski (1882 - 1969) Polish mathematician, best known for the Sierpinski triangle and the Sierpinski numbers.

Sierpinski studied physics and mathematics at the University of Warsaw, graduating in 1903, then went for a doctorate at university in Kraków. In 1908 he started teaching at the University of Lwów. A prolific author of books and papers, Sierpinski wrote on many subjects but focused on irrational numbers and set theory. During World War I, Sierpinski was stuck in Russia, but the experience proved useful when he returned to Poland and helped his comrades break Russian cryptography. During this time he also founded and edited the journal Fundamenta Mathematicae. From 1929 to the end of his life, he received various honors at home and abroad. In 1964, he was elected to the London Mathematical Society.

In 1954, Sierpinski published a French paper on some properties of Euler's totient function and the sum of divisors function in Bull. Acad. Polon. Sci. Cl. III 2 with Andrzej Schinzel, who a few years later co-authored with Erdos a paper on the ``Distributions of the values of some arithmetical functions'' in Acta Arithmetica 6, giving Sierpinski an Erdos number of 2.