Question

How to calculate the Collatz sequence starting with 13 in PHP

Answer 1

function CalcCollatz($x) {
    if (($x & 1) != 0) {
        return $x * 3 + 1;
    }
    
    return $x / 2;
}

function PrintCollatzSequence($x) {
    echo $x . " ";
    
    while ($x != 1) {
        $x = CalcCollatz($x);
        echo $x . " ";
    }
}
        
$x = 13;
PrintCollatzSequence($x);




/*
run:

13 40 20 10 5 16 8 4 2 1 

*/

 

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