Max is stacking logs at his campground for firewood. After his first load of logs, he has 9 logs on the stack. After his seventh load of logs, he has 51 logs on the stack. Use sequence notation to represent the arithmetic function.
A an = 51 + 6(n − 1)
B an = 9 + 6(n − 1)
C an = 51 + 7(n − 1)
D an = 9 + 7(n− 1)