Question

Here is an interesting sequence: 11, 21, 49, 107, 207, 361, X, Y, Z, ..... Can anyone show me what the values of X, Y, & Z are? In addition, can you calculate the 100th number in this sequence? Thanks for your help.

Answer 1

\[2n ^{3}-3n ^{2}+5n+7\]

When n=7, X = 581
When n=8, Y = 879
When n=9, Z = 1267
When n=100, \[N _{100}\] = 1970507

Answer 2

Thanks so much for your help! I really appreciate this.