Determine a general formula (in terms of n) for the sum of the first n positive integers that are not divisible by 5.

(In reply to re: Different formula, same result by tomarken)

Well, thanks for the kind words, but I am not convinced that mine is any more elegant than yours.  Yours uses smaller numbers, so the pencil and paper calculation might actually be easier.

Posted by Steve Herman on 2014-03-18 16:48:27