This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A330032 #23 Jul 03 2025 04:42:23
%S A330032 1,2,26,9366,204495126,460566381955706,162249649997008147763642,
%T A330032 12595124129900132067036747870669270,
%U A330032 288398561903310939256721956218813835167026180310,2510964964470962082968627390938311899485883615067802615950711482
%N A330032 The number of chains of strictly rooted upper triangular or lower triangular matrices of order n.
%C A330032 Also, the number of chains in the power set of (n^2-n)/2-elements such that the first term of the chains is either an empty set or a set of (n^2-n)/2-elements.
%C A330032 The number of rooted chains of 2-element subsets of {0,1, 2, ..., n} that contain no consecutive integers.
%C A330032 The number of distinct rooted reflexive symmetric fuzzy matrices of order n.
%C A330032 The number of chains in the set consisting of all n X n reflexive symmetric matrices such that the first term of the chains is either reflexive symmetric matrix or unit matrix.
%H A330032 Alois P. Heinz, <a href="/A330032/b330032.txt">Table of n, a(n) for n = 0..28</a>
%H A330032 S. R. Kannan and Rajesh Kumar Mohapatra, <a href="https://arxiv.org/abs/1909.13678">Counting the Number of Non-Equivalent Classes of Fuzzy Matrices Using Combinatorial Techniques</a>, arXiv preprint arXiv:1909.13678 [math.GM], 2019.
%H A330032 R. B. Nelsen and H. Schmidt, Jr., <a href="http://www.jstor.org/stable/2690450">Chains in power sets</a>, Math. Mag., 64 (1) (1991), 23-31.
%H A330032 M. Tărnăuceanu, <a href="http://www.jstor.org/stable/2690450">The number of chains of subgroups of a finite elementary abelian p-group</a>, arXiv preprint arXiv:1506.08298 [math.GR], 2015.
%F A330032 a(n) = A000629((n^2-n)/2).
%Y A330032 Cf. A000629, A038719, A007047, A328044, A330301, A330302, A330804, A331957.
%K A330032 nonn
%O A330032 0,2
%A A330032 S. R. Kannan, _Rajesh Kumar Mohapatra_, Feb 29 2020
%E A330032 Missing term a(6) = 162249649997008147763642 inserted by _Georg Fischer_, Jul 15 2024