A general term formula sequence 2, - 6,18, - 54. A general term formula

A general term formula sequence 2, - 6,18, - 54. A general term formula

This is an equal ratio sequence with the first term of 2 and the common ratio of - 3
a2=2(-3)
a3=2(-3)²
a4=2(-3)³
...
an=2(-3)^(n-1)