Recaman sequence

recaman.swift

// Usage
// recaman(size: 10)
// ouput: [0, 1, 3, 6, 2, 7, 13, 20, 12, 21]

import Foundation

func recaman(size: Int) -> [Int] {
    var res = [Int]()
    var counter = 1
    var currNumber = 0
    
    for index in 0..<size {
        if index == 0 {
            res.append(currNumber)
            continue
        }
        let aux = currNumber - counter
        if aux > 0 && !res.contains(aux) {
            currNumber = aux
        } else {
            currNumber = currNumber + counter
        }
        res.append(currNumber)
        counter += 1
    }
    
    return res
}