Did you know in R, : and c() are different when you want to create a numeric vector?
See the example below.
> x <- 1:2 > y <- c(1, 2) > identical(x, y)  FALSE > typeof(x)  "integer" > typeof(y)  "double"
So, : produces integers while c() produces floating-point number.
Reference: The Art of R Programming by Norman Matloff