Convert LAT in Ytile value


I try to convert LAT in YTile values.
Reading the wiki I got the formulas. And with this converter I got the values that the formulas should yield to.

For Zoom equal to 12 and LAT equal to 53.051600, the Ytile value should be 1333

But when I use the formula:

ytile := Floor((1 - Log( Tan(Lat * Pi / 180) + 1 / Cos(Lat * Pi / 180)) / Pi ) / 2 * 2** zoom)

I get YTile = 1737. and this is the wrong value.

Where have I done something wrong?

Thank you.
That was the problem. I had to use LN()
Much appreciated