Krillins Function

Krillin has found a new recursive function $K(n)$ having value: - $0$ , if $n$ = $0$ - $7*K(n-1)$ + $3*n$ + $4$ , if $n$ > $0$ - $Not$ $defined$, if $n$ < $0$ He calculated $K(n)$ for some values of $n$. But then he realized that it would be better if he gets a programmer to write a program for him to calculate $K(n)$. He is offering $100$ points in Crack-A-Code 1.0 to anyone who could write