斐波那契数列是否有 R function ？

Question

Function in R, again, call it "f1", that takes n as an input, so f1<-function(n) {} and computes a Fibonacci sequence up to the value n, but where the sequence sums the last three rather than only last 2 numbers. So the sequence is 1 1 1 3 5 9 17...

Answer 1

Try this code

f <- function(n) {
  v <- numeric(n)
  for (i in seq(n)) {
    if (i <= 3) {
      v[i] <- 1
    } else {
      v[i] <- sum(v[i - (1:3)])
    }
  }
  v
}

and you will see

> f(10)
 [1]   1   1   1   3   5   9  17  31  57 105