7 card 21 for dealer probabilities

Hi,.

I am a dealer here in Puerto Rico and wanted to ask for some mathematical information regarding the following things that I have noticed on a blackjack game. Also, has anyone seen a dealer make a 21 with a hand of seven cards?

1. I once made a 7 card 21 (as a dealer) and wanted to know the probabilities of making this hand when the dealer stands on all 17's. The specific hand was
A, 2, 3, 6, A, A, 7
but I know that there are other combinations for 7 card 21. The other day I almost made it with
A, 2, 2, 7, A, 3, K (I busted on the last king but had all of the players saying "no 5!!!").

Rules:
A. Dealer stands on all 17's
B. 6 card deck that gets cut to 4.5

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I think that hurts just as much, the only disadvantage to the player is that the dealer has to hit soft 17 and the odds make it easier to make a larger H17 hand with 9 cards.

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If you play a lot of shoe games, you'll see the dealer draw a 7 card 21 often enough that you'll just take it in stride. I've seen an 8 card 21 more than a few times.

Somewhere I have the data for a S17 game -- here is H17.

For 2 deck H17 (without double checking, sorry), there are 1952 different ways the dealer can make a seven card 21 and the probability on any one hand is 0.00002349 for a seven card 21.

For 6 deck H17, there are still 1952 different ways the dealer can make a seven card 21, (after all, you'll never use more than seven of any card) and the probability on any one hand is 0.00002925 (1-in-34187 hands) for a seven card 21.

For S17, I have the followig numbers for dealer 21 with 7 cards.
0,0000232846308826644
That's 1 in 42.947 hands.
And there are 1.541 different ways that it can be done.