probability

within a 72 hand set of blackjack i am looking for the probability of this which all happened in seperate instances

the dealer got or pulled 21 in 3 out of 4 consecutive hands
the dealer got back to back blackjacks
the dealer got or pulled 21 in 4 out of 6 consecutive hands
the dealer got or pulled 21 in 3 consecutive hands
the dealer got or pulled 21 in 3 out of 6 consecutive hands

Going to need much more information than that.
How many decks?
H17 or S17?
How far was the penetration?

blackjack at online casino
always stood on 17

so here you go. all separate instances within a 72 hand set

first instance (4 out of 6 consecutive hands)
player 15 dealer 4 card 21
player 7 dealer blackjack
player 20 dealer 3 card 21
player 15 dealer blackjack

second instance (2 consecutive hands)
player 13 dealer blackjack
player 13 dealer blackjack

third instance (3 out of 4 consecutive hands)
player 18 dealer blackjack
player 15 dealer blackjack
player 20 dealer blackjack

fourth instance (3 consecutive hands)
player 15 dealer 3 card 21
player 19 dealer 3 card 21
player 19 dealer 3 card 21

fifth instance (3 out of 6 consecutive hands)
player 20 dealer 3 card 21
player 20 dealer 3 card 21
player 20 dealer 3 card 21