0,2

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.

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.

Cf. A120608, A120587, A006602.

Sequence in context: A144295 A119489 A053631 this_sequence A038791 A001696 A013333

Adjacent sequences: A120615 A120616 A120617 this_sequence A120619 A120620 A120621

nonn,more

Alan Veliz-Cuba (alanavc(AT)vt.edu), Jun 18 2006