Since posted, the Reddit thread has is filled with people speculating what the answer might be.
"This is a binomial probability density function with an error. The term after the sigma is not a fraction but a combination ... To find the answer for the question, you need the value of N, the number of coin flips," wrote one user.
"I don't know if this is a trick question or not, but to me that says the password is some variation of 'One', '1' 'One Hundred Percent' or '100%'," wrote another.