login
Smallest multiple of n with a number of divisors >= n.
0

%I #5 Sep 16 2015 13:07:54

%S 1,2,6,8,20,12,42,24,36,60,132,60,312,168,120,240,612,180,912,240,420,

%T 660,1380,360,900,1560,1080,840,3480,720,3720,1440,1980,3060,1260,

%U 1260,8880,4560,3120,1680,14760,2520,15480,3960,2520,8280,16920,3360,8820

%N Smallest multiple of n with a number of divisors >= n.

%C Also add a(n)/n as a separate sequence; first 8 terms are 1,1,2,2,4,2,6,3.

%e a(8) = 24 because 8 has only 4 divisors and 16 has only 5, but 24 has 8 and so 24 qualifies.

%t a = {}; For[n = 1, n < 50, n++, i = 1; While[DivisorSigma[0, i*n] < n, i++ ]; AppendTo[a, n*i]]; a (* _Stefan Steinerberger_, Aug 28 2008 *)

%K nonn

%O 1,2

%A _J. Lowell_, Jul 27 2008

%E More terms from _Stefan Steinerberger_, Aug 28 2008