2785693domain: NAppears in sequencesa(n) = (Sum_{k=1..A047380(n)} k^6) / (Sum_{k=1..A047380(n)} k^2).at n=28A133180a(n) = 1 + 27n + 252n^2 + 882n^3 + 1029n^4.at n=7A134158