Proof step

Ore-algebra identity of two definitions

All-n equality of two definitions

Concludes

shift_x_plus_one of basis_map_A013610 of Triangle of Bessel numbers read by rows: T(n,k) is the number of k-matchings of the complete graph K(n).

Premises

none: a direct theorem check

Theorem

polytool ?

Checked

polytool replayed · Lean not attempted