A fair Coin is tossed times. Let be the absolute difference in the number of
heads and tails obtained. Then the probability distribution is given by
See also Bernoulli Distribution, Coin, Coin Tossing
References
Handelsman, M. B. Solution to Problem 436, ``Distributing `Heads' Minus `Tails.''' College Math. J. 22,
444-446, 1991.