A000883 Number of switching networks with C(2,n) acting on the domain and AG(2,2) acting on the range. (Formerly M1956 N0774)

2, 9, 443, 11211435, 24019199779842731, 221537999297485986455406144733751979, 37692737381938865697777013349182261812327566685142592258699083037385861803

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

Vincenzo Librandi, Table of n, a(n) for n = 1..10

Index entries for sequences related to switching networks

Formula

a(n) = (4^(2^n) - 4*2^(2^n) + 8*2^n + 10*2^(n+2^n))/(24*2^n). - Sean A. Irvine, Jan 24 2012

Mathematica

Table[(4^(2^n)-4*2^(2^n)+8*2^n+10*2^(n+2^n))/(24*2^n), {n, 0, 11}] (* Vincenzo Librandi, Mar 28 2012 *)

Prog

(Magma) [(4^(2^n)-4*2^(2^n)+8*2^n+10*2^(n+2^n))/(24*2^n):n in [1..11]]; // Vincenzo Librandi, Mar 28 2012
(PARI) a(n)=my(N=2^n); (2^(2*N-n)-4<<(N-n)+8+10<<N)/24 \\ Charles R Greathouse IV, Mar 28 2012

Crossrefs

Sequence in context: A049299 A024225 A266289 * A086693 A085605 A336247

Adjacent sequences: A000880 A000881 A000882 * A000884 A000885 A000886

Keyword

nonn,easy

Author

N. J. A. Sloane

Extensions

More terms from Sean A. Irvine, Jan 23 2012

Status

approved