A q-multinomial expansion of LLT coefficients and plethysm multiplicities
Lascoux, Leclerc and Thibon (1997) [9] introduced a family of symmetric polynomials, called LLT polynomials. We prove a q-multinomial expansion of the coefficients of LLT polynomials in the case where @m=(@m,...,@m)@?n and define a q-analog of a sum of the plethysm multiplicities.