A074807 Number of steps needed to reach a prime when the following map is repeatedly applied to n: if n is even then 2n + POD(n) + 1, otherwise 2n - POD(n) - 1, where POD(n) is the product of the digits of n; or -1 if no prime is ever reached.

2, 1, 1, 1, 2, 1, 2, 4, 5, 4, 2, 4, 3, 5, 5, 3, 5, 3, 2, 1, 3, 2, 3, 4, 3, 4, 3, 1, 3, 1, 2, 1, 4, 6, 3, 3, 5, 1, 2, 6, 6, 5, 1, 5, 2, 4, 4, 2, 1, 1, 8, 4, 2, 2, 3, 3, 3, 1, 6, 2, 4, 1, 1, 5, 3, 2, 3, 6, 1, 2, 2, 5, 2, 4, 2, 5, 5, 2, 5, 13, 5, 1, 2, 2, 2, 7, 4, 1, 5, 1, 2, 3, 4, 4, 4, 7, 3, 1, 2, 2, 2, 2, 2, 4