### de Bruijn Card Trick

Before christmas I showed you some sequences called de Bruijn sequences. They're designed to contain every combination of some numbers without any repeats http://youtu.be/iPLQgXUiU14For example, this sequence 1111222212211212 contains every combination of 1 and 2 of length 4. So 1111 is in there, 2212 is in there. And this sequence wraps round, so 1211 is in there, but wrapped around.But instead of 1 and 2, let's call this Black and Red. So the sequence becomes BBBB RRRR BRRB BRBRWe are going to memorise 16 cards in that order. These are my 16 cardsAc5s9cKs 2h6d10hAd 3c7hJd2s 4c8hQs3dSo the blocks of four start with Ace, 2, 3, 4. Then the other cards in each block just add four. So Ace, 5, 9, King. And I've tried to keep the suits in CHSD order. So the first block is club spade club spade, the last block is in actual CHSD order. The third block needed a bit of a switch.I do this three times, using three decks, to make a pack that is 3 times 16 cards. 48 cards.The cuts don't affect the sequence. So if you can identify the red cards. You should know where in the sequence you are. And can name those four cards.For example, if the first second and fourth person have a red card, then we are looking for RRBR, which is 10hAd3c7h.That will take some practice, or a cheat sheet, but it can be done.

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