Converting Odd Integer Series to Sigma Notation

[brianaIScool]

1. Write each series using sigma notation.
2. The series is:

2 + 5 + 10 + 17 + 26 + 37
3. I know that above the sigma, the number is 6 because there are only six terms in the series. The trouble I seem to have with this is the fact that the series is neither arithmetic or geometric. It increases by consecutive odd integers. I don't know how to figure the notation for this series.

 

[berkeman]

1. Write each series using sigma notation.



2. The series is:

2 + 5 + 10 + 17 + 26 + 37



3. I know that above the sigma, the number is 6 because there are only six terms in the series. The trouble I seem to have with this is the fact that the series is neither arithmetic or geometric. It increases by consecutive odd integers. I don't know how to figure the notation for this series.

Hint -- Each odd number can be written as twice some number plus one...