This is the pattern,
800(1), 2*800(1), 3*800(2), 4*800(2), 5*800*(3) now, in the
end, there is 6400 which seems like the number, in the end, is
reduced, there is only one such number is the series, so it will be
very difficult to guess without options or one more number in the
series to know the next one. for now, the series can have multiple
The problem is not really about products, more about finding an arrangement of digits 1 to N-1 (for base N, since digit N does not exist in base N), that conforms to the criterion that any pair in the arrangement is part of the set of single digit products.
There could be a better way to solve this, but I wrote a small program that creates a table of ...