09 What is the Jacobsthal Sequence?

A001045 – OEIS

The Jacobsthal sequence is named after the German mathematician Ernst Jacobsthal. It is formed with the formula

The first numbers are
0,
1,
1,
3,
5,
11,
21,
43,
85,
171,
341,
683,
1365,
2731,
5461,
10923,
21845,
43691,
87381,
174763,
349525,
699051,
1398101,
2796203,
5592405,
11184811,
22369621,
44739243,
89478485,
178956971,
357913941,
715827883,
1431655765,
2863311531,
5726623061