447188domain: NAppears in sequencesNumber of compositions of 2n where the multiplicity of the first part equals n.at n=13A332051a(n) = Sum_{1 <= m <= n} Sum_{1 <= k <= n+1-m} m*R(k,n+1), where R(k,b) = (b^k - 1)/(b - 1) is the base-b repunit of length k.at n=7A332082