More Delta. The (Unofficial) Russian Doll Method - Find Leading Term

Using the Delta Difference Operator again, to understand the composition of sequences and series, will get a specific result of finding the leading term of a polynomial.

To clarify, @ 06:00, just FOIL the expression as if (a+b)(a+b) then factor.

It's as straight forward as a Russian doll of finding the least doll.

Sources:

Gelfand, Gerver, Kirillov, Konstantinov and Kushnirenko - Sequences: 1969, problem 20