Looping for infinitely decreasing input

General
2

Welcome to the community!

Is implementing this in an easy way your question? But I think your implementation is not correct? It indicates 16 as prime, which is not. See below:

prime <- function(x) {
  a <- seq_len(x)
  b <- length(a[(x %% a) == 0])
  if (b > 2) {
    c <- seq_len(x - 1)
    d <- length(c[(x - 1) %% c == 0])
    if (d > 2) {
      "true"
    }
  }
}

prime(x = 16)
#> [1] "true"

Created on 2019-03-20 by the reprex package (v0.2.1)

I've just no idea why have you done this. If there are only two factors, then they have to be unity and the number itself. So, you can conclude about prime or not prime only from b.

Again, I can't follow why do you expect this will be the case. Your code doesn't check either for either case.

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