$a_1 = 1$ ↵
$a_2 = 5$ ↵
$a_n = a_{n-1} + n^2(a_{n-2}+1)$↵
↵
**Prove** $a_n=(n+1)!-1$ ↵
P.S. [Original problem](https://artofproblemsolving.com/wiki/index.php/Induction#Intermediate)
$a_2 = 5$ ↵
$a_n = a_{n-1} + n^2(a_{n-2}+1)$↵
↵
**Prove** $a_n=(n+1)!-1$ ↵
P.S. [Original problem](https://artofproblemsolving.com/wiki/index.php/Induction#Intermediate)
