Square-factorial numbers: a(1) = 1, a(n+1) = a(n) * largest square divisor of (n+1).

Terms

a(0) =1a(1) =1a(2) =1a(3) =4a(4) =4a(5) =4a(6) =4a(7) =16a(8) =144a(9) =144a(10) =144a(11) =576a(12) =576a(13) =576a(14) =576a(15) =9216a(16) =9216a(17) =82944a(18) =82944a(19) =331776a(20) =331776a(21) =331776a(22) =331776a(23) =1327104a(24) =33177600a(25) =33177600a(26) =298598400a(27) =1194393600a(28) =1194393600a(29) =1194393600