Sequences with Adjacent Elements Unequal
Some general problems on the number of parts in partitions
Some Parity Statistics in Integer Partitions
We study integer partitions with respect to the classical word statistics of levels and descents subject to prescribed parity conditions. For instance, a partition with summands may be enumerated according to descents while tracking the individual parities of and . There are two types of parity levels, E = E and O = O, and four types of parity-descents, E > E, E > O, O > E and O > O, where E and O represent arbitrary even and odd summands. We obtain functional equations and explicit...
Some properties of associated Stirling numbers.
Some results on derangement polynomials
We study moments of the difference concerning derangement polynomials . For the first moment, we obtain an explicit formula in terms of the exponential integral function and we show that it is always negative for . For the higher moments, we obtain a multiple integral representation of the order of the moment under computation.
Sorting classes.
Strings with maximally many distinct subsequences and substrings.
Sums involving moments of reciprocals of binomial coefficients.