477463domain: NAppears in sequencesa(n) = (Sum_{k=1..A047380(n)} k^6) / (Sum_{k=1..A047380(n)} k^2).at n=18A133180a(n) = 163 + 1053*n + 2520*n^2 + 2646*n^3 + 1029*n^4.at n=4A134160