Exercise 8 Page 447

The given rule means that, after the first term of the sequence, every term $a_n$ is the difference between the square of the previous term $a_{n-1}$ and $10.$

$a_1=1,$ $a_2=\text{-}9,$ $a_3=71,$ $a_4=5031,$ $a_5=25310951,$ $a_6=640644240524391$