Answer: 67,108,863 combinations.
Explanation:
We have 13 blocks.
Each block has 4 differet options.
The total number of combinations is equal to the product of the options for each variable (the variables are the 13 blocks) so we have that the number of combinations is:
C = 4*4*4*4*4*4*4*4*4*4*4*4*4 = 4^13 = 67,108,863