
Let \(\{a_i\}^n_{i=1}\) be a sequence of natural numbers, \(0\leq a_i\leq n\) for \(i=1,\dots,n\), and \(A_{nm}\) be an \(n\times m\) array associated with this sequence, whose entries \(\alpha_{ij}=0,1\) such that \(\sum_{j=1}^m \alpha_{ij}=a_i\), \(i=1,\dots,n\), \(j=1,\dots,m\). A path of order \(k\) along \(A_{nm}\) is said to be a sequence of entries \(\alpha_{ij_1},\dots,\alpha_{nj_n}\) for which \(\sum_{i=1}^n \alpha_{ij_i}=k\), \(k=0,1,\dots,n\), \(j_ i=1,\dots,m\), \(i=1,\dots,n\). The authors deduce that the number of such paths in the case \(m=n\), denoted by \(g^k(a_,\dots,a_n;n),\) is equal to \((-1)^k\sum_{m=k}^n \binom{m}{k}s_n(n,n-m)n^{n-m}\) where \(s_j(j,i)\) is the generalized Stirling number of the first kind associated with the numbers \(a_1,\dots,a_j\): \((x-a_1)\dots(x-a_j)=\sum_{\ell =0}^j s_j(j,\ell)x^{\ell}\), introduced by \textit{L. Comtet} [C. R. Acad. Sci., Paris, Sér. A 275, 747--750 (1972; Zbl 0246.05006)]. Furthermore, the generating function of the numbers \(g^k(1,\dots,n;n)\) is obtained.
generating function, Computational Theory and Mathematics, Exact enumeration problems, generating functions, Bell and Stirling numbers, Geometry and Topology, generalized Stirling number, binary array, Combinatorial aspects of matrices (incidence, Hadamard, etc.), Theoretical Computer Science
generating function, Computational Theory and Mathematics, Exact enumeration problems, generating functions, Bell and Stirling numbers, Geometry and Topology, generalized Stirling number, binary array, Combinatorial aspects of matrices (incidence, Hadamard, etc.), Theoretical Computer Science
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