Greatest 4th-power-free divisor of n!

Terms

a(0) =1a(1) =2a(2) =6a(3) =24a(4) =120a(5) =45a(6) =315a(7) =2520a(8) =280a(9) =175a(10) =1925a(11) =23100a(12) =300300a(13) =4204200a(14) =63063000a(15) =63063000a(16) =1072071000a(17) =14889875a(18) =282907625a(19) =9053044a(20) =190113924a(21) =4182506328a(22) =96197645544a(23) =144296468316a(27) =22787343150a(28) =660832951350