# There are exactly two values of n for which Sn = 861

Consider the following statements in respect of the expression

S_{n} = n (n + a)/2

where n is an integer:

1. There are exactly two values of n for which S_{n} = 861

2. S_{n} = S_{-(n + 1)} and hence for nay integer m, we have two values of n for which S_{n} = m

Which of the above statements is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2