Approximating reals by rationals of the form a/b^2

Oleg Karpenkov

Published 2006-10-24, updated 2006-10-30Version 2

In this note we formulate some questions in the study of approximations of reals by rationals of the form a/b^2 arising in theory of Shr"odinger equations. We hope to attract attention of specialists to this natural subject of number theory.