In below formula for arithmetic sequence you can fill in a=7 (start), d=2 (interval) and n=35 (nr terms) and you get
17.5(14 + 34*2) = 1435
Confirmed by a brute-force addition: 7+9+11+13+15+17+19+21+23+25+27+29+31+33+35+37+39+41+43+45+47+49+51+53+55+57+59+61+63+65+67+69+71+73+75=1435
