Product of squarefree numbers less than n+1.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =6a(5) =30a(6) =180a(7) =1260a(8) =1260a(9) =1260a(10) =12600a(11) =138600a(12) =138600a(13) =1801800a(14) =25225200a(15) =378378000a(16) =378378000a(17) =6432426000a(18) =6432426000a(19) =122216094000a(20) =122216094000