Zigzag Number Spiral - Closed Form Expression
Zigzag Number Spiral By Susam Pal on 27 Jul 2025 \[ \gdef\lf{\hspace{-5mm}\leftarrow\hspace{-5mm}} \gdef\rt{\hspace{-5mm}\rightarrow\hspace{-5mm}} \gdef\up{\uparrow} \gdef\dn{\downarrow} \gdef\sp{} \gdef\cd{\cdots} \gdef\vd{\vdots} \gdef\dd{\ddots} \gdef\arraystretch{1.2} \gdef\hl{{\small\blacktriangleright}} \] Consider the following infinite grid of numbers, where the numbers are arranged in a spiral-like manner, but the spiral reverses direction each time it reaches the edge of the grid: \