There are 52 terms in the sequence. If you divide each of the numbers in 2: 2,4,6,...,102,104 = 1,2,3,...,51,52.

2+104 = 4+102 = 6+100 which means ((2+104)x52)/2 equals the sum of the sequence, which is 2756, and if you divide that by 7 you get 393 r5.

So, the answer is 5.