521338domain: NAppears in sequencesL.g.f.: Sum_{n>=1} a(n)*x^n/n = Sum_{n>=1} x^n/n * exp( Sum_{k>=1} 2*a(n*k)*x^(n*k)/k ).at n=8A203265Number of non-isomorphic multiset partitions of weight n into singletons or strict pairs.at n=18A339888