Chapter 9, Problem 12E

Consider the sequence $1,2,6,24,120,\mathrm{...}$.

a. List the next two terms of the sequence.

b. Assuming that the sequence is denoted by $A_1,A_2,A_3,\mathrm{...}$, give an explicit formula for $A_N$.

c. Assuming that the sequence is denoted by $P_0,P_1,P_2,\mathrm{...}$, give an explicit formula for $P_N$.