Congruences modulo powers of 5 and 7 for the crank and rank parity functions and related mock theta-functions
摘要
It is well known that Ramanujan conjectured congruences modulo powers of 5, 7 and 11 for the partition function. These were subsequently proved by Watson (J. Reine Angew. Math. 179:97–128, 1938) and Atkin and O’Brien (Trans. Am. Math. Soc. 126:442–459, 1967). In 2009 Choi, Kang, and Lovejoy proved congruences modulo powers of 5 for the crank parity function. The generating function for the analogous rank parity function is f(q), the first example of a mock theta-function that Ramanujan mentioned in his last letter to Hardy. Recently we proved congruences modulo powers of 5 for the rank parity function, and here we extend these congruences for powers of 7. We also show how these congruences imply congruences modulo powers of 5 and 7 for the coefficients of the related third order mock theta-function