Concepts2
∑MathAdvanced
Generating Functions - EGF
Exponential generating functions (EGFs) encode a sequence (a_n) as A(x) = \sum_{n \ge 0} a_n \frac{x^n}{n!}, which naturally models labeled combinatorial objects.
#exponential generating function#egf#binomial convolution+11
∑MathAdvanced
Stirling Numbers of First Kind
Stirling numbers of the first kind count permutations by their number of cycles and connect power polynomials to rising/falling factorials.
#stirling numbers of the first kind#unsigned cycle numbers#signed stirling numbers+12