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 A328888 #9 Feb 16 2025 08:33:58
%S A328888 1,1,1,1,6,1,1,18,18,1,1,46,132,46,1,1,110,696,696,110,1,1,254,3150,
%T A328888 6728,3150,254,1,1,574,13086,51760,51760,13086,574,1,1,1278,51492,
%U A328888 348048,632970,348048,51492,1278,1,1,2814,195180,2143736,6466980,6466980,2143736,195180,2814,1
%N A328888 Array read by antidiagonals: T(n,m) is the number of acyclic edge covers of the complete bipartite graph K_{n,m}.
%C A328888 In other words, the number of spanning forests of the complete bipartite graph K_{n,m} without isolated vertices.
%H A328888 Andrew Howroyd, <a href="/A328888/b328888.txt">Table of n, a(n) for n = 1..1275</a>
%H A328888 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CompleteBipartiteGraph.html">Complete Bipartite Graph</a>
%F A328888 T(n,m) = A072590(n, m) + Sum_{i=1..n-1} Sum_{j=1, m-1} binomial(n-1, i-1) * binomial(m, j) * A072590(i, j) * T(n-i, m-j).
%e A328888 Array begins:
%e A328888 =============================================================
%e A328888 n\m | 1 2 3 4 5 6 7
%e A328888 ----+--------------------------------------------------------
%e A328888 1 | 1 1 1 1 1 1 1 ...
%e A328888 2 | 1 6 18 46 110 254 574 ...
%e A328888 3 | 1 18 132 696 3150 13086 51492 ...
%e A328888 4 | 1 46 696 6728 51760 348048 2143736 ...
%e A328888 5 | 1 110 3150 51760 632970 6466980 58620030 ...
%e A328888 6 | 1 254 13086 348048 6466980 96208632 1231832364 ...
%e A328888 7 | 1 574 51492 2143736 58620030 1231832364 21634786586 ...
%e A328888 ...
%o A328888 (PARI)
%o A328888 T(n, m=n)={my(M=matrix(n, m), N=matrix(n, m, n, m, n^(m-1) * m^(n-1))); for(n=1, n, for(m=1, m, M[n,m] = N[n,m] + sum(i=1, n-1, sum(j=1, m-1, binomial(n-1, i-1)*binomial(m, j)*N[i,j]*M[n-i, m-j])))); M}
%o A328888 { my(A=T(7)); for(i=1, #A, print(A[i,])) }
%Y A328888 Column 2 is A328890.
%Y A328888 Main diagonal is A328889.
%Y A328888 Cf. A072590, A328887.
%K A328888 nonn,tabl
%O A328888 1,5
%A A328888 _Andrew Howroyd_, Oct 29 2019