Mathematical miscellany

Parabolic geometry

• Basic conformal tractor geometry ($B_n / P_1$, $D_n / P_1$) computations
• Basic data for Legendrean contact geometry ($A_n / P_{1n}$)
• Classification of parabolic curvature operators of high order ($>2$)
• Classification of nonrigid harmonic curvature components of parabolic geometries given by binary forms

Other

• $n$-gonal numbers that are squares of $n$-gonal-numbers
• A hexagon-tiling problem of Dan Finkel (original Twitter thread)