a(0)=1, a(n) = largest divisor of n! that is coprime to a(n-1).

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =8a(5) =15a(6) =16a(7) =315a(8) =128a(9) =2835a(10) =256a(11) =155925a(12) =1024a(13) =6081075a(14) =2048a(15) =638512875a(16) =32768a(17) =10854718875a(18) =65536a(20) =262144a(22) =524288a(24) =4194304a(26) =8388608a(28) =33554432a(30) =67108864