missing number

It's always possible to find another number in any sequence!  For example, consider the function:

f(n) = - (19/6)n⁴ + (175/6)n³ - (235/3)n² + (421/3)n - 9

n        f(n)

1          79

2        141

3        238

4        355

5        401

6        209

Of course, this might not be the sequence the questioner had in mind!

Does not have a sequence.