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A118224
Smallest number having at least 2*n divisors.
3
2, 6, 12, 24, 48, 60, 120, 120, 180, 240, 360, 360, 720, 720, 720, 840, 1260, 1260, 1680, 1680, 2520, 2520, 2520, 2520, 5040, 5040, 5040, 5040, 5040, 5040, 7560, 7560, 10080, 10080, 10080, 10080, 15120, 15120, 15120, 15120, 20160, 20160, 25200, 25200, 25200
OFFSET
1,1
LINKS
FORMULA
A000005(a(n)) >= 2*n;
a(n) = A061799(2*n).
a(n) <= A003680(n). - Michael S. Branicky, Feb 06 2021
MATHEMATICA
s={}; Do[i=1; Until[DivisorSigma[0, i]>=2n, i++]; AppendTo[s, i], {n, 45}]; s (* James C. McMahon, Sep 24 2024 *)
PROG
(Python)
from sympy import divisors
def a(n):
m = 4*n - 2
while len(divisors(m)) < 2*n: m += 1
return m
print([a(n) for n in range(1, 46)]) # Michael S. Branicky, Feb 06 2021
CROSSREFS
Cf. A086921, A003680 (exactly 2n).
Sequence in context: A307211 A294545 A305104 * A227068 A003680 A337257
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Apr 16 2006
STATUS
approved