

A003180


Number of equivalence classes of Boolean functions of n variables under action of symmetric group.
(Formerly M1265 N1405)


15




OFFSET

0,1


COMMENTS

A003180(n1) is the number of equivalence classes of Boolean functions of n variables from Post class F(8,inf) under action of symmetric group.
Also number of nonisomorphic sets of subsets of an nset.
Also the number of unlabeled hypergraphs on n nodes [Qian].  N. J. A. Sloane, May 12 2014
In the 1995 Encyclopedia of Integer Sequences this sequence appears twice, as both M1265 and M3458 (one entry began at n=0, the other at n=1).


REFERENCES

M. A. Harrison, Introduction to Switching and Automata Theory. McGraw Hill, NY, 1965, p. 147.
D. E. Knuth, The Art of Computer Programming, Vol. 4A, Section 7.1.1, p. 79.
S. Muroga, Threshold Logic and Its Applications. Wiley, NY, 1971, p. 38, Table 2.3.2.  Row 5.
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

Vladeta Jovovic, Table of n, a(n) for n = 0..11
Toru Ishihara, Enumeration of hypergraphs, European Journal of Combinatorics, Volume 22, Issue 4, May 2001.
S. Muroga, Threshold Logic and Its Applications, Wiley, NY, 1971 [Annotated scans of a few pages]
Jianguo Qian, Enumeration of unlabeled uniform hypergraphs, Discrete Math. 326 (2014), 6674. MR3188989. See Table 1, p. 71.  N. J. A. Sloane, May 12 2014
Marko Riedel, Cycle indices for the enumeration of nonisomorphic hypergraphs
Marko Riedel, Implementation of the Ishihara algorithm for cycle indices of the action of the symmetric group S_n on sets of subsets of an nset.
Index entries for sequences related to Boolean functions


FORMULA

a(n) = Sum_{1*s_1+2*s_2+...=n} (fix A[s_1, s_2, ...]/(1^s_1*s_1!*2^s_2*s_2!*...)) where fix A[s_1, s_2, ...] = 2^Sum_{i>=1} ( Sum_{di} ( mu(i/d)*( 2^Sum_{j>=1} ( gcd(j, d)*s_j))))/i.


MAPLE

with(numtheory):with(combinat):
for n from 1 to 10 do
p:=partition(n): s:=0: for k from 1 to nops(p) do q:=convert(p[k], multiset): for i from 0 to n do a(i):=0: od:
for i from 1 to nops(q) do a(q[i][1]):=q[i][2]: od:
c:=1: ord:=1: for i from 1 to n do c:=c*a(i)!*i^a(i):ord:=lcm(ord, i): od: ss:=0:
for i from 1 to ord do if ord mod i=0 then ss:=ss+phi(ord/i)*2^add(gcd(j, i)*a(j), j=1..n): fi: od:
s:=s+2^(ss/ord)/c:
od:
printf(`%d `, n):
printf("%d ", s):
od: # Vladeta Jovovic, Sep 19 2006


CROSSREFS

a(n) = 2*A000612(n). Cf. A001146. Row sums of A052265.
Sequence in context: A141522 A114903 A038054 * A002080 A001206 A144295
Adjacent sequences: A003177 A003178 A003179 * A003181 A003182 A003183


KEYWORD

nonn,nice


AUTHOR

N. J. A. Sloane


EXTENSIONS

More terms from Vladeta Jovovic, Sep 19 2006
Edited with formula by Christian G. Bower, Jan 08 2004


STATUS

approved



