Coefficients of a substitution `T ↦ Y, X ↦ 0` (or `T ↦ 0, X ↦ Y`) into one-variable power series: the `n`-th coefficient is the coefficient of `Y^n` on the surviving axis `t`.

Initializing...

Coefficients of a substitution `T ↦ Y, X ↦ 0` (or `T ↦ 0, X ↦ Y`) into one-variable power series: the `n`-th coefficient is the coefficient of `Y^n` on the surviving axis `t`. · Prove2Me