Proof step

Ore-algebra identity of two definitions

All-n equality of two definitions

Concludes

shift_x_plus_one of basis_map_A013609 of Triangle read by rows, T(n,k) = T(n-1,k) + T(n-2,k) + T(n-1,k-1) + T(n-2,k-1) and T(0,0) = 1.

Premises

none: a direct theorem check

Theorem

polytool ?

Checked

polytool replayed · Lean not attempted