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 A000869 Number of switching networks with C(2,n) acting on domain and GL(3,Z2) acting on range. (Formerly M3620 N1470) 1
 4, 27, 14056, 104751025086, 14737381492157353997140846, 583807825091767184801127161305581049499763751729421166 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Next term has 112 digits. - Sean A. Irvine, Jan 24 2012 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 Vincenzo Librandi, Table of n, a(n) for n = 1..10 EXAMPLE a(n) = (8^(2^n) + 22*2^(2^n + 2^(n-1) + n) - 22*2^(2^n + 2^(n-1)) + 21*4^(2^n) + 56*2^(2^n) + 42*2^(n + 2^n) + 56*2^(2^(n-1) + n) - 56*2^(2^(n-1)) + 48*2^n)/(168*2^n). - Sean A. Irvine, Jan 24 2012 PROG (MAGMA) [(8^(2^n)+22*2^(2^n+2^(n-1)+n)-22*2^(2^n+2^(n-1))+21*4^(2^n)+56*2^(2^n)+42*2^(n+2^n)+56*2^(2^(n-1)+n)-56*2^(2^(n-1))+48*2^n)/(168*2^n): n in [1..11]]; // Vincenzo Librandi, Mar 28 2012 CROSSREFS Sequence in context: A008973 A132646 A254866 * A132640 A174212 A038706 Adjacent sequences:  A000866 A000867 A000868 * A000870 A000871 A000872 KEYWORD nonn,easy AUTHOR EXTENSIONS More terms from Sean A. Irvine, Jan 23 2012 STATUS approved

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