21 BlocksMath brain teasers require computations to solve.One day, Drakar was studying for an algebra test when he noticed that his younger sibling made a pyramid of 21 blocks. Each row, from the bottom up, had one less block than the lower one.
"Hmm, I wonder how many different pyramids I can make. Now, I can only switch the blocks with other blocks on the row. So blocks in the fourth row can only be switched with other blocks from the fourth row. And I can switch blocks from as many rows I like, and count it as one different pyramid." After thinking for a minute he took out a calculator and quickly figured out the answer. How many different pyramids can be made? 
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