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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. 2
0, 32, 27648, 258473984, 34924795002880, 73692421593384353792, 2475385863878910456755126272, 1329190247836700110425361699261382656, 11417938846687390120116281062224453749176270848, 1569274711573306070659025854469940650153499575743856771072 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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.

LINKS

Table of n, a(n) for n=1..10.

C. W. Wu, Conditions for separability in generalized Laplacian matrices and diagonally dominant matrices as density matrices, Physics Letters A, 351 (2006), 18-22.

C. W. Wu, Graphs whose normalized Laplacian matrices are separable as density matrices in quantum mechanics, arXiv:1407.5663, 2014.

FORMULA

A245290(n) + A245291(n) = 2^(n*(2*n-1))-1.

A245291(n) = 2^(n*(2*n-1))-2^(n*(n-1))*A229865(n).

CROSSREFS

Cf. A245290, A229865.

Sequence in context: A230914 A232596 A123393 * A016937 A074800 A320859

Adjacent sequences:  A245288 A245289 A245290 * A245292 A245293 A245294

KEYWORD

nonn

AUTHOR

Chai Wah Wu, Jul 16 2014

STATUS

approved

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Last modified September 20 03:51 EDT 2019. Contains 327210 sequences. (Running on oeis4.)