Here's my best attempt

Assume that the only two integers are 1 and 3.......and.....the number of 3s is one more than the number of 1s

So....

[3(n + 1) + 1(n) ]

______________ < 2.1

2n + 1

4n + 3 < 4.2n + 2.1

.9 < .2n

9/2 < n

n = 5

1 1 1 1 1 3 3 3 3 3 3

We need 11 integers