  It is well known that Ramanujan conjectured congruences modulo powers of 5, 7
and and 11 for the partition function. These were subsequently proved by Watson
(1938) and Atkin (1967). In 2009 Choi, Kang, and Lovejoy proved congruences
modulo powers of 5 for the crank parity function. The generating function for
rank parity function is f(q), which is the first example of a mock theta
function that Ramanujan mentioned in his last letter to Hardy. We prove
congruences modulo powers of 5 for the rank parity function.

Number Theory;Combinatorics