Question

Find the next two terms in the sequence –5, 8, –13, 20, –29, …. Write a formula for the nth term. Identify the formula as explicit or recursive.

Answer 1

I'll just let -5 be the 1st term:
\[a_n=(-1)^n(a_{n-1}+2n-1)\]

Answer 2

(-1)^n *(n^2+4)
the next two terms are 40,-53