You can do something like this in each table - (Column A has your
sequential numbers. This formula would be in column B). Sort Column
A first:

=IF(A3<A2+1,"Error","OK")

In this example, create a new column (B) next to your sequential
column (A). Assuming the numbers are formatted as numbers, and they
are sequential in increments of 1, this will tell you where the gaps
are.

Copy this formula down the column. Then sort by column B and you will
immediately see the gaps next to the word "Error"