Beginning with n = 1, write the first four terms of the sequences whose nth terms, or general terms, are:
a) an = 3+(-1)^(n+1)
b) an = (n+1)! / 2^n
A sequence defined recursively has the formula a1 = -2 and an = -3an-1+4 for n ≥ 2. Compute the first four terms of the sequence.