This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A120618 #2 May 11 2007 03:00:00
%S A120618 1,2,4,12,90,3831
%N A120618 Number of inequivalent (under "inversion of variables") monotone Boolean functions of n or fewer variables.
%C A120618 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 A120618 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 A120618 Cf. A120608, A120587, A006602.
%K A120618 nonn,more
%O A120618 0,2
%A A120618 Alan Veliz-Cuba (alanavc(AT)vt.edu), Jun 18 2006