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%I #2 May 11 2007 03:00:00
%S 1,2,4,12,90,3831
%N Number of inequivalent (under "inversion of variables") monotone Boolean functions of n or fewer variables.
%C We define the "inversion of variables", i, by (i.f)(x1,...,xn)=1+f(1+x1,...,1+xn). Note that {i,identity function} is a group. It turns out that if f is a monotone function, then i.f is also a monotone function. f is equivalent to g if f=g or f=i.g.
%e a(1)=2 because m(x)=0,n(x)=1,k(x)=x are the three monotone Boolean functions (of 1 or fewer variables) and m,n are equivalent.
%Y Cf. A120608, A120587, A006602.
%K nonn,more
%O 0,2
%A Alan Veliz-Cuba (alanavc(AT)vt.edu), Jun 18 2006
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