A000824 - OEIS

%I M4917 N2110 #27 Dec 08 2023 12:06:03

%S 13,237,356026,2932175712336,412646680050205587085305856,

%T 16346619102569481158480824333166611354489546429742186496

%N Number of switching networks (see Harrison reference for precise definition).

%C Number of equivalence classes with complementation of n variables on the domain and symmetric group of 3 variables operating on the range. - _Sean A. Irvine_, Jul 11 2011

%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H M. A. Harrison, <a href="https://doi.org/10.1016/0016-0032(63)90456-3">On the number of classes of switching networks</a>, J. Franklin Instit., 276 (1963), 313-327.

%H <a href="/index/Sw#switching">Index entries for sequences related to switching networks</a>

%F Let b_n(r,s) = (2^(r*2^n) + (2^n-1)*2^(s*2^(n-1)))/2^n. Then, a(n) = (b_n(3,3) + 3*b(2,3) + 2*b(1,1))/6. - _Sean A. Irvine_, Jul 11 2011

%t b[n_, r_, s_] := (2^(r*2^n) + (2^n - 1)*2^(s*2^(n - 1)))/2^n; a[n_] := (b[n, 3, 3] + 3*b[n, 2, 3] + 2*b[n, 1, 1])/6;Table[a[n],{n,6}] (* _James C. McMahon_, Dec 07 2023 *)

%K nonn

%O 1,1

%A _N. J. A. Sloane_

%E More terms from _Sean A. Irvine_, Jul 10 2011