  R. L. Graham and H. O. Pollak observed that the sequence $$u_1=1,\qquad
u_{n+1}=\lfloor \sqrt{2} (u_n+1/2)\rfloor, \quad n\geq 1,$$ has the curious
property that the sequence of numbers $(u_{2n+1}-2u_{2n-1})_{n\geq 1}$ 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.

Number Theory;Combinatorics