Smallest number not yet used that is either a divisor or multiple of both n and a(n-1).

Terms

a(0) =1a(1) =2a(2) =6a(3) =12a(4) =60a(5) =3a(6) =21a(7) =168a(8) =504a(9) =2520a(10) =27720a(11) =4a(12) =52a(13) =364a(14) =5460a(15) =21840a(16) =371280a(17) =1113840a(18) =21162960a(19) =5a(20) =105a(21) =2310a(22) =53130a(23) =212520a(24) =1062600a(25) =13813800a(26) =124324200a(27) =7a(28) =203a(29) =6090