Sequence 1, 5, 14, 30, 55, 91 The 12th number in is______ .

Sequence 1, 5, 14, 30, 55, 91 The 12th number in is______ .

1+22+32+42+52+… +122, = 1 + 4 + 9 + 16 + 25 + 36 + 49 + 64 + 81 + 100 + 121 + 144, = 650; answer: the 12th number is 650