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A000838
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Number of n-input 2-output switching networks under action of complementing group on the inputs and outputs.
(Formerly M3629 N1474)
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1
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OFFSET
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1,1
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REFERENCES
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M. A. Harrison, On the number of classes of switching networks, J. Franklin Instit., 276 (1963), 313-327.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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FORMULA
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a(n) = 2^(2^(n+1) - 2 - n) + 2^(2^n) - 2^(2^n-n). - Sean A. Irvine, Jul 14 2011
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EXAMPLE
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G.f. = 4*x + 28*x^2 + 2272*x^3 + 67170304*x^4 + 144115192236605440*x^5 + ...
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MATHEMATICA
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a[ n_] := If[ n < 1, 0, 2^(2^(n + 1) - 2 - n) + 2^2^n - 2^(2^n - n)]; (* Michael Somos, Aug 17 2015 *)
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PROG
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(PARI) {a(n) = if( n<1, 0, 2^(2^(n+1) - 2 - n) + 2^(2^n) - 2^(2^n - n))}; /* Michael Somos, Sep 07 2013 */
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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