Let be the binary linear code
How many binary linear codes are there which are equivalent (under coordinate permutations) to ?
[THOUGHT] To determine the number of binary linear codes equivalent to under coordinate permutations, I need to count the distinct ways to permute the coordinates of while preserving its structure. The code consists of 8 pairs of identical bits, so any equivalent code must also have this structure of 8 pairs.
The problem can be seen as equivalent to the number of ways to partition the 16 coordinates into 8 unordered pairs. This is a classic combinatorial problem. The formula for the number of ways to partition items into unordered pairs is given by:
For , we get:
I will calculate this using Python to ensure accuracy. [/THOUGHT] [PYTHON] import math
n = 8 result = math.factorial(2*n) // (2**n * math.factorial(n)) print(result)
[THOUGHT] Based on the Python output, the number of binary linear codes equivalent to under coordinate permutations is 2027025. This confirms the calculation of the number of ways to partition 16 coordinates into 8 unordered pairs. [/THOUGHT] \boxed{2027025}