%N Inverse function of N -> N injection A075175.
%C a(n) = 0 for those n which do not occur as the values of A075175. All positive natural numbers occur here once.
%Y a(A075175(n)) = n for all n >= 1. Differs from A075174 for first time at a(18) = 9, while A075174(18) = 0.
%A _Antti Karttunen_, Sep 13 2002