OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..89 (terms 1..60 from Michael De Vlieger)
EXAMPLE
a(4)=12 has 6 divisors. Checking the multiples of 5: 1*5=5 has 2 divisors. 2*5=10 has 4 divisors. 3*5=15 has 4 divisors. 4*5=20 has 6 divisors. 5*5=25 has 3 divisors. So the first 5 positive multiples of 5 each have <= 6 divisors. But 6*5 = 30 has 8 divisors. And since 8 > 6, a(5) = 30.
MATHEMATICA
FoldList[Block[{d = DivisorSigma[0, #1], k = 1, m}, While[DivisorSigma[0, Set[m, k #2]] <= d, k++]; m] &, Range@ 37] (* Michael De Vlieger, Aug 29 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Jul 28 2008
EXTENSIONS
a(9)-a(37) from Donovan Johnson, Sep 05 2008
STATUS
approved