A fancy way to obtain the binary digits of $759250125\sqrt{2}$

Abstract

R. L. Graham and H. O. Pollak observed that the sequence $$u_1=1,u_{n+1}=\lfloor \sqrt{2}(u_n+1/2)\rfloor ,n\ge 1,$$ has the curious property that the sequence of numbers $(u_{2n+1}-2u_{2n-1}{)}_{n\ge 1}$ denotes the binary digits of $\sqrt{2}$. We present an extension of Graham--Pollak's sequence which allows to get -- in a fancy way -- the binary digits of $759250125\sqrt{2}$ and other numbers.

7 pages, 2 figure