I currently stand on point A, somewhere in Europe.
When I do my sequence here and if I start with 25, I get the following sequence:
25, 13, 7, 5, 4, 4, 4, 4, x, ...
When I step a few metres to the Southwest, I get the following sequence:
25, 10, 3, 5, 4, 6, 3, 5, y, ...
When I step a few metres to the East, I get the following sequence:
25, 14, 8, 4, 4, 4, 4, 4, z, ...
Here $x,y,z$ are yet unknown integers, and the dots signify that the sequence continues indefinitely to the right. You may start to find $x,y,z$, but the harder question and actual puzzle is:
Where is point A?