Least k such that n+1 is the n-th divisor of k.

Terms

a(0) =3a(1) =4a(2) =20a(3) =12a(4) =84a(5) =120a(6) =360a(7) =360a(8) =3960a(9) =2520a(10) =32760a(11) =27720a(12) =27720a(13) =55440a(14) =942480a(15) =720720a(16) =13693680a(17) =12252240a(18) =12252240a(19) =12252240a(20) =281801520a(21) =232792560a(22) =1163962800a(23) =1163962800a(24) =3491888400a(25) =3491888400a(26) =101264763600a(27) =80313433200