A bacterial colony starts with $50$ bacteria and doubles every hour. Let $B_n$ represent the $n$^th term of the sequence, where $B_1$ is the initial count. Write an explicit formula and find $B_6$.

• A. $B_n=50\cdot 2^{n-1}$ $B_6=1,600$
• B. $B_n=50\cdot 2^n$ $B_6=3,200$
• C. $B_n=50+2(n-1)$ $B_6=60$
• D. $B_n=50{\left(\frac{1}{2}\right)}^{n-1}$ $B_6=\frac{50}{32}$