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Search: id:A006237
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| A006237 |
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Complexity of tensor sum of n graphs; or spanning trees on n-cube.
(Formerly M3725)
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+0
2
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| 1, 1, 4, 384, 42467328, 20776019874734407680, 1657509127047778993870601546036901052416000000, 15385084434981466048710053999438117828156794239305576125756067764471886924847513\ 6000000000000000000000
(list; graph; listen)
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OFFSET
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0,3
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
G. Kreweras, Complexite et circuits Euleriens dans la sommes tensorielles de graphes, J. Combin. Theory, B 24 (1978), 202-212.
R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Example 5.6.10.
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LINKS
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Index entries for sequences related to trees
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FORMULA
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a(n) = 2^(2^n-1-n)*1^binomial(n, 1)*2^binomial(n, 2)*...*n^binomial(n, n).
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PROGRAM
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(PARI) a(n)=2^(2^n-n-1)*prod(k=1, n, k^binomial(n, k))
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CROSSREFS
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Cf. A006235.
Adjacent sequences: A006234 A006235 A006236 this_sequence A006238 A006239 A006240
Sequence in context: A154569 A038015 A003753 this_sequence A116031 A115049 A158111
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KEYWORD
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nonn,easy,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), D. E. Knuth
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EXTENSIONS
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Description expanded 7/95.
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