A000868 Number of switching networks with C(2,n) acting on domain and GL(2,Z2) acting on range. (Formerly M3580 N1451)

4, 21, 1531, 44782251, 96076794891512491, 886151997189943927518995693301312171, 150770949527755462791108053396729046910357127815416821444325531778055580331

Offset

1,1

Comments

Next term has 151 digits. - Sean A. Irvine, Jan 23 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

Index entries for sequences related to switching networks

Formula

a(n) = (2^(2^(n+1)) + 2^(n+2 + 2^n) - 2^(2^n) + 2^(n+1))/(3*2^(n+1)). - Sean A. Irvine, Jan 23 2012

Crossrefs

Sequence in context: A118909 A225157 A158947 * A000875 A094046 A326603

Adjacent sequences: A000865 A000866 A000867 * A000869 A000870 A000871

Keyword

nonn

Author

N. J. A. Sloane

Extensions

More terms from Sean A. Irvine, Jan 22 2012

Status

approved