Question

Write a possible explicit rule for the nth term of the sequence: 5, 10, 20, 40, 80, ...

Answer 1

5, 10, 20, 40, 80, ...

$5, 5\times2, 5\times4, 5\times8, 5\times16, ... \\ \\5\times 2^0, 5\times2^1, 5\times2^2, 5\times2^3, 5\times2^4, ... \\ \\a_n=5\times 2^{n-1},n\in N$