For independent fair dice, the probability of avoiding one on each die is . Therefore
The complement of an event gives
For this separable differential equation, away from , separation gives , or on a connected interval. The initial condition gives , hence
The maximal interval containing on which this solves the printed differential equation is . Although the linear formula extends through one, the right-hand side there is and the original equation is undefined. The equilibrium solution , lost if one divides by , does not satisfy the initial condition.
Put . The values , , and give the Taylor expansion
The factorial in the quadratic term accounts for its coefficient .
The first partial derivatives factor as
Both vanish at the origin, verifying that it is a stationary point. Since , every stationary point has ; the first equation then gives . Thus one requested additional point is ; the other is .
The integrand is an even function, since both and are odd functions. Using integration by parts,
The endpoint cosine terms vanish, leaving the sine contribution.

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