260.
Subtract the nth number from the (n+1)st. You get 2, 4, 8, 14, ?
Do it again for that sequence. You get 2, 4, 6, ?
Maybe that sequence is 2, 4, 6, 8, 10, 12, 14, 16, 18, ...
If so, then the sequence "above" it is 2, 4, 8, 14, 22, 32, 44, 58, 74, ...
And the original sequence is 2, 4, 8, 16, 30, 52, 84, 128, 186, 260, ...
