Single integer in R

i am generating random number by using uniform distribution. As i understood x must be single integer. When i assign x as integer as below. It seems like not any more random number generating, because it is giving me same numbers. Could you someone help me how to assign x as a single integer in below function?

Xn <- function(n, x, a, b, M) {
  x <- integer(n) #i think i did wrong here.
  x <- (a * x + b) %% M
  y <- x/M
  return(y)
}
x <- runif(10, min = 0, max = 1)
Xn(n = 10, x = x, a = 568, b = 19580, M = 89138)