a(n) is the smallest integer that has exactly n alternating divisors.

Terms

a(0) =1a(1) =2a(2) =4a(3) =6a(4) =16a(5) =12a(6) =24a(7) =48a(8) =36a(9) =96a(10) =72a(11) =144a(12) =210a(13) =180a(14) =420a(15) =360a(16) =504a(17) =864a(18) =630a(19) =1080a(20) =1512a(21) =2160a(22) =1260a(23) =3150a(24) =1890a(25) =2520a(26) =5040a(27) =6300a(28) =3780a(29) =10080