15034586596domain: NAppears in sequencesa(1)=1, a(n) = n*21^(n-1) + a(n-1).at n=7A014938a(n) = 1 + 2*n + 3*n^2 + 4*n^3 + 5*n^4 + 6*n^5 + 7*n^6 + 8*n^7.at n=21A113618