How to properly use the predict function in R

Question

I'll start by giving you some startup code.

library(ggplot2)

y = c(0, 0, 1, 2, 0, 0, 1, 3, 0, 0, 3, 0, 6, 2, 8, 16, 21, 39, 48, 113, 92, 93 ,127, 159, 137, 46, 238, 132 ,124, 185 ,171, 250, 250 ,187, 119 ,151, 292, 94, 281, 146, 163 ,104, 156, 272, 273, 212, 210, 135, 187, 208, 310, 276 ,235, 246, 190, 232, 254, 446,

314, 402 ,276, 279, 386 ,402, 238, 581, 434, 159, 261, 356, 440, 498, 495, 462 ,306, 233, 396, 331, 418, 293 ,431 ,300, 222, 222, 479 ,501, 702

,790, 681)

x = length; 1 (y)

Currently, I'm attempting to forecast the 90th data point using polynomial regression, where data points #1 and #89 are both 0.