Question

which two numbers are next in the sequence: 1,3,7,15?

Answer 1

you can see, 3-1=2
7-3=2^2
15-7=2^3

Answer 2

so the differences are in gp, first term is 2, common ratio is 2 .. now try to find out the next numbers

Answer 3

\[a_0 =1\\
a_n = a_{n-1} + 2^n\\
a_5=??
\]