

A000838


Number of ninput 2output switching networks under action of complementing group on the inputs and outputs.
(Formerly M3629 N1474)


1




OFFSET

1,1


REFERENCES

M. A. Harrison, On the number of classes of switching networks, J. Franklin Instit., 276 (1963), 313327.
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

Table of n, a(n) for n=1..7.
Index entries for sequences related to switching networks


FORMULA

a(n)=2^(2^(n+1)2n)+2^(2^n)2^(2^nn). [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

Cf. A000133, A000839.
Sequence in context: A203279 A081792 A084594 * A218174 A220756 A202713
Adjacent sequences: A000835 A000836 A000837 * A000839 A000840 A000841


KEYWORD

easy,nonn


AUTHOR

N. J. A. Sloane.


EXTENSIONS

More terms from Vladeta Jovovic, Feb 26 2000


STATUS

approved



