Generalized higher order spt-functions

Abstract

We give a new generalization of the spt-function of G.E. Andrews, namely $\operatorname {Spt}_{j}(n)$, and give its combinatorial interpretation in terms of successive lower-Durfee squares. We then generalize the higher order spt-function $\operatorname {spt}_{k}(n)$, due to F.G. Garvan, to ${}_{j\!}\operatorname {spt}_{k}(n)$, thus providing a two-fold generalization of $\operatorname {spt}(n)$, and give its combinatorial interpretation. Lastly, we show how the positivity of _j spt _k (n) can be used to generalize Garvan’s inequality between rank and crank moments to the moments of j-rank and (j+1)-rank.