Yet Another Random

YAR.js

var YAR = function(nseed) {
    var seed, constant = Math.pow(2, 13) + 1,
        prime = 37,
        maximum = Math.pow(2, 50);
    if (nseed) {
        seed = nseed;
    }
    if (seed == null) { 
        seed = (new Date()).getTime();
    }
    return {
        next: function() {
            seed *= constant;
            seed += prime;
            seed %= maximum;
            return seed;
        }
    }
}

How to use:

var random = new YAR(20);
random.next();