OLL 42
The algorithm, how to recognise it and how to practise it without cheating.
Recommended algorithm
R' U' R U' R' U2 R F R U R' U' F'13 moves
How to recognise it
Yellow on top: the left and front edges and the two back corners, with headlights on the front side.
Its inverse is another case
Do the 42 algorithm backwards, F U R U' R' F' R' U2 R U R' U R, and you are solving 41.
That's why CubeDojo never scrambles 42 that way: it builds a random state with the case fixed, so you practise 42 and not 41.
Practise 42 now
Random-state scrambles, a timer and spaced review. Free, on the web and on your phone.