606440100domain: NAppears in sequencesa(n) = 280*binomial(n+4,9) + 280*binomial(n+4,8) + 105*binomial(n+3,7) + 77*binomial(n+3,6) + 43*binomial(n+2,5) - 16*binomial(n+2,4) + 20*binomial(n+1,3) - floor(n*(n^2 - 1)*(n^2 - 4)*(n-3)/360).at n=20A064204