fun fib(n: Int): Int
    if n <= 1
        return 1
    else
        return fib(n-1) + fib(n-2)

fun **(x: Float, p: Int): Float
    var res = 1.0
    for i = 0..p
        res *= x
    return res

fun collatzLen(n: Int): Int
    var m = n
    var len = 1
    while m > 1
        ++len
        if m % 2 == 0
            m /= 2
        else
            m = m*3 + 1
    return len

fun sprMain
    cout << "Fibonacci numbers:" << endl
    for i = 0..10
        cout << "  fib(" << i << ") = " << fib(i) << endl

    cout << "Powers of 2.0:" << endl
    for i = 0..8
        cout << "  2.0 ** " << i << " = " << (2.0 ** i) << endl

    cout << "Collatz sequence lengths:" << endl
    for i = 1...20
        cout << "  collatz(" << i << ") = " << collatzLen(i) << endl