function registerBackIn(name, amount) {
    registerEasing([name, function (percentComplete, startValue, endValue) {
        if (percentComplete === 0) {
            return startValue;
        }
        if (percentComplete === 1) {
            return endValue;
        }
        return Math.pow(percentComplete, 2) * ((amount + 1) * percentComplete - amount) * (endValue - startValue);
    }]);
}
Converting from hex as it makes for a smaller file.