$$a_n=\{Y_n,X_n\}$$

where $X_n$ is sequence <A HREF="https://oeis.org/A319572">A319572</A> and $Y_n$ is sequence <A HREF="https://oeis.org/A319573">A319573</A> in the OEIS database. These are the coordinates of the stripe enumeration of $N \times N$ where $N = \{0, 1, 2, \ldots\}$.