-1 -4 -10 -11 -1 26 76
-3 -6 -1 10 27 50
-3 5 11 17 23
8 6 6 6
-2 0 0
2 0
-2
Calculate the differences between each pair of elements in the sequence. Then calculate the differences between each pair of differences, and so on until you get a row with more than one element where all of the elements are the same. This only works when you have a convergent sequence. Unfortunately, your given sequence does not converge, hence the differences method is inconclusive.
The only way I know to get the next element in the sequence is to assign a sequential x value to each of the sequence elements forming a set of ordered pairs of the form
and then find a polynomial of degree
that fits the data. Your next element will be
where
is the derived polynomial. To do this you either use a graphing app that has a curve fitting utility, or you grind a 7X7 system of linear equations.
My graph program gave me
and then calculated
John

My calculator said it, I believe it, that settles it
