%I

%S 1,16,240,17293822569102704640

%N a(1) = 1, for n >= 2, a(n) = the smallest number m with (a(n-1) + 4) divisors.

%F A000005(a(n)) = a(n-1) + 4 for n >= 2.

%e a(3) = 240 = the smallest number with 16 + 4 = 20 divisors.

%Y Cf. A014221, A175718, A175719.

%K nonn

%O 1,2

%A _Jaroslav Krizek_, Aug 15 2010