Question 90
If $n$ is a composite number, denote $D_n$ its largest proper divisor. A number $n$ will be called *squarish* if the number $D_n + D_{n+1}$ is a perfect square.
a) Show that $35$, $76$ and $755$ are squarish.
b) Show that there are infinitely many squarish numbers.
a) Show that $35$, $76$ and $755$ are squarish.
b) Show that there are infinitely many squarish numbers.