The classic 176 point sunspot data from 1749-1924 that has been widely modeled
data("sunspot.classic")
The format is: num [1:176] 80.9 83.4 47.7 47.8 30.7 12.2 9.6 10.2 32.4 47.6 ...
"Applied Time Series Analysis with R, 2nd edition" by Woodward, Gray, and Elliott