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A000838 Number of n-input 2-output switching networks under action of complementing group on the inputs and outputs.
(Formerly M3629 N1474)
1
4, 28, 2272, 67170304, 144115192236605440, 1329227995784915891062320757838184448, 226156424291633194186662080095093570363541849729447858357132587076662853632 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
REFERENCES
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).
LINKS
FORMULA
a(n) = 2^(2^(n+1) - 2 - n) + 2^(2^n) - 2^(2^n-n). - Sean A. Irvine, Jul 14 2011
G.f.: A(x) = G(0) - 1; G(k) = 1 + (8*2^k - 8 + 8^2^k*x*G(k+1))/2^(2^k+1). - Sergei N. Gladkovskii, Dec 02 2011 [edited by Michael Somos, Sep 07 2013]
EXAMPLE
G.f. = 4*x + 28*x^2 + 2272*x^3 + 67170304*x^4 + 144115192236605440*x^5 + ...
MATHEMATICA
a[ n_] := If[ n < 1, 0, 2^(2^(n + 1) - 2 - n) + 2^2^n - 2^(2^n - n)]; (* Michael Somos, Aug 17 2015 *)
PROG
(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 */
CROSSREFS
Sequence in context: A354842 A084594 A334598 * A218174 A220756 A202713
KEYWORD
easy,nonn
AUTHOR
EXTENSIONS
More terms from Vladeta Jovovic, Feb 26 2000
STATUS
approved

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Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)