cp's OEIS Frontend

Sequence given by the Hankel transform (see A001906 for definition) of A081178 = {1, 1, 8, 71, 680, 6882, 72528, 788019, ...}; example: det([1, 1, 8, 71; 1, 8, 71, 680; 8, 71, 680, 6882; 71, 680, 6882, 72528]) = 7^6 = 117649.

In general, sequences of the form m^((n^2 - n)/2) enumerate the graphs with n labeled nodes with m types of edge. a(n) therefore is the number of labeled graphs with n nodes with 7 types of edge. - Mark Stander, Apr 11 2019

Sequence given by the Hankel transform (see A001906 for definition) of A082147 = {1, 1, 9, 89, 945, 10577, 123129, 1476841, ...}; example: det([1, 1, 9, 89; 1, 9, 89, 945; 9, 89, 945, 10577; 89, 945, 10577, 123129]) = 8^6 = 262144.

The number of labeled multigraphs on n vertices such that (i) no self loops are allowed; (ii) all edges are painted in one of 3 colors; (iii) edges between any pair of vertices are painted in distinct colors. Note, this implies that there are at most 3 edges between any vertex pair. Also note there is no restriction on the color of edges incident to a common vertex. - Geoffrey Critzer, Jan 14 2020

Sequence given by the Hankel transform (see A001906 for definition) of A082148 = {1, 1, 11, 131, 1661, 22101, 305151, 4335711, ...}; example: det([1, 1, 11, 131; 1, 11, 131, 1661; 11, 131, 1661, 22101; 131, 1661, 22101, 305151]) = 10^6 = 1000000.

Also the Hankel transform of A379103. - Nathaniel Johnston, Dec 16 2024

Sequence given by the Hankel transform (see A001906 for definition) of A082173 = {1, 1, 12, 155, 2124, 30482, 453432, 6936799, ...}; example : det([1, 1, 12, 155; 1, 12, 155, 2124; 12, 155, 2124, 30482; 155, 2124, 30482, 453432]) = 11^6 = 1771561.