Student wrote:

Does the sequence always start at one as opposed to 0?

A sequence starts with the first element.

If you think of the first element as of the zero one, then you must shift all other elements accordingly. So if a question asks you to calculate the sum of the 10th and the 20th terms, then in your notation it will be the sum of the 9th and 19th terms.

Student wrote:

I used S*n* = 11*n* + 8 and got the trap answer of 346. Please advise.

If you notate the first element as S

*0* (S

*0* = 8), then the 10th one will be S

*9* and the 20th one will be S

*19*.