538257874441domain: NAppears in sequencesNumber of compositions of 3n in which the minimal multiplicity of parts equals n.at n=21A244174a(n) = binomial(2*n-2, n-1) + (-1)^n.at n=21A286033a(n) = binomial(2*(n - 1), n - 1) + 1.at n=22A323230