Fibonacci sequence (0 omitted)

fibonacci.php

function fibonacci($n)
{
    //$fib = [0,1] // use this if you don't want to omit '0'
    $fib = [1,1];
    for($i=1;$i<$n;$i++)
    {
        $fib[] = $fib[$i]+$fib[$i-1];
    }
    //print_r($fib);
    echo $fib[$n];
}
fibonacci(4); // = 5