Question

Compute 900-841+784+...+36-25+16-9+4-1

Answer 1

If I understand your sequence, then this is the "closed form" of the sequence:

 a_n = 63 - 4 n

Sum = (59, 55, 51, 47, 43, 39, 35, 31, 27, 23, 19, 15, 11, 7, 3) = 465