Finding the next available lowest number in a sequence

[cjcreamer]

Hello,

I need help creating a formula that returns the next available lowest number in a sequence. In this example I would need the formula to return a value between 1-64 from looking at G3-G66. The formula can be placed in J3. In the example attached, I would need it to return "4". Once that ID is taken, the next number available the formula should return should be 24.

Many thanks for any and all help!