8+6+4+2+0+(-2)+(-4)+(-6)+(-8)+(-10)+(-12)+(-14)+(-16)+(-18)+(-20)+(-22)+(-24)+(-26)+(-28)+(-30)+(-32) = -252
By formula, where a1 = first term, an = nth term,
n = number of term(s), d = common difference between any term after the first,
and the preceding term. Sn = sum of first n terms.
Edwin
