yeah i got 63 too, but in a different way i think.
basically, the differences between them respectively, are 1, 7, 5, 11, 9, and 15.
divide it like this: 1, 7, 5, and 11, 9, 15
then take the sum of the last two digits in the first set, and subtract the first. so in this case, 7 + 5...