The first group -8, 10, 18, 28, 46, 74, 120. ......

Group 2 -3, 13, 16, 29, 45, 74, 1 19. ......

Let a2-a1= m.

Then a6=8a 1+5m=74,

And a7= 13a 1+8m.

It is known that a 1 and m are natural numbers.

8a 1 is an even number, so m is an even number, 5m is a multiple of 10, and 74-5m is divisible by 8.

So a 1=8, m = 2；; Or a 1 = 3, m = 10.

When a 1=8 and m=2, a7= 120.

When A 1 = 3 and M = 10, a7= 1 19.