Chapter 4 - Section 4.6 - Cryptography - Supplementary Exercises - Page 308: 22

$7,37,67,97,127,157$

The constant difference must be divisible by 6 because of having 6 terms. Also, it must be divisible by 5 because it will otherwise run into a number that is 0 mod 5. Trying the product, 30, we get the sequence above, which works.