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 A366252 #12 Jan 22 2024 07:42:28
%S A366252 1,1,6,227,37617,23750562,56091061929
%N A366252 Number of convergent binary relations on [n] (A365534) that converge to a quasi-order relation (A000798).
%C A366252 Equivalently, a(n) is the number of convergent Boolean relation matrices whose Frobenius normal form is such that all the diagonal blocks are primitive (A070322).
%H A366252 D. A. Gregory, S. Kirkland, and N. J. Pullman, <a href="https://doi.org/10.1016/0024-3795(93)90323-G">Power convergent Boolean matrices</a>, Linear Algebra and its Applications, Volume 179, 15 January 1993, Pages 105-117.
%H A366252 E. de Panafieu and S. Dovgal, <a href="https://arxiv.org/abs/1903.09454">Symbolic method and directed graph enumeration</a>, arXiv:1903.09454 [math.CO], 2019.
%H A366252 D. Rosenblatt, <a href="https://nvlpubs.nist.gov/nistpubs/jres/67B/jresv67Bn4p249_A1b.pdf">On the graphs of finite Boolean relation matrices</a>, Journal of Research of the National Bureau of Standards, 67B No. 4, 1963.
%F A366252 Sum_{n>=0} a_n*x^n/(2^n*binomial(n,2)) = 1/(E(x) @ exp(-(p(x)-1))) where E(x) = Sum_{n>=0} x^n/(2^n*binomial(n,2)), p(x) is the e.g.f. for A070322, and @ is the exponential Hadamard product (see Panafieu and Dovgal).
%t A366252 nn = 6; B[n_] := 2^Binomial[n, 2] n!; pr[x_] := Total[primitive Table[x^i/i!, {i, 0, 6}]];ggf[egf_] := Normal[Series[egf, {x, 0, nn}]] /.
%t A366252 Table[x^i ->x^i/2^Binomial[i, 2], {i, 0, nn}];Table[B[n], {n, 0, nn}] CoefficientList[Series[1/ggf[Exp[- (pr[x] - 1)]], {x, 0, nn}], x]
%Y A366252 Cf. A070322, A365534, A000798, A366218.
%K A366252 nonn,more
%O A366252 0,3
%A A366252 _Geoffrey Critzer_, Oct 05 2023