This is the second Google puzzle that I discussed at BarCamp way back last year. You can get your own personalised question from Google at http://treasurehunt.appspot.com/.
The basis of the puzzle is to find sequences of prime numbers that sum to prime numbers. Copying the example from the Google page, if you have sequences of 3 and 6 prime numbers then the smallest prime sum you can have is 41 which is:
The sequence lengths are quite long, for example I've just been asked for the smallest prime sum for sequences of lengths 19, 21, 405 and 781.