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 A245291 #19 Jul 24 2023 04:53:31 %S A245291 0,32,27648,258473984,34924795002880,73692421593384353792, %T A245291 2475385863878910456755126272,1329190247836700110425361699261382656, %U A245291 11417938846687390120116281062224453749176270848,1569274711573306070659025854469940650153499575743856771072 %N A245291 Number of normalized graph Laplacian matrices of nonempty labeled graphs of 2n vertices that are entangled in C^2 x C^n as density matrices in quantum mechanics. %C A245291 Since entanglement is not invariant under graph isomorphism, all 2^(n(2n-1))-1 nonzero Laplacian matrices are treated as different. A nonzero Laplacian matrix not equal to the complete graph is entangled in C^2 x C^n if and only if its complement is. Since the complete graph is not entangled, this means that a(n) is even for all n. %H A245291 Chai Wah Wu, <a href="http://dx.doi.org/10.1016/j.physleta.2005.10.049">Conditions for separability in generalized Laplacian matrices and diagonally dominant matrices as density matrices</a>, Physics Letters A, 351 (2006), 18-22. %H A245291 Chai Wah Wu, <a href="http://arxiv.org/abs/1407.5663">Graphs whose normalized Laplacian matrices are separable as density matrices in quantum mechanics</a>, arXiv:1407.5663 [quant-ph], 2014. %F A245291 A245290(n) + a(n) = 2^(n*(2*n-1))-1. %F A245291 a(n) = 2^(n*(2*n-1))-2^(n*(n-1))*A229865(n). %Y A245291 Cf. A245290, A229865. %K A245291 nonn %O A245291 1,2 %A A245291 _Chai Wah Wu_, Jul 16 2014