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A175749
Numbers with 40 divisors.
4
1680, 2160, 2640, 3024, 3120, 3240, 3696, 4080, 4368, 4536, 4560, 4752, 5520, 5616, 5670, 5712, 6000, 6160, 6384, 6864, 6960, 7128, 7280, 7344, 7440, 7680, 7728, 8208, 8424, 8880, 8910, 8976, 9520, 9744, 9840, 9936, 10032, 10320, 10368, 10416, 10530, 10608
OFFSET
1,1
COMMENTS
Numbers of the forms p^39, p^19*q^1, p^9*q^3, p^7*q^4, p^9*q^1*r^1, p^4*q^3*r^1 (A179698), and p^4*q^1*r^1*s^1 (A179693), where p, q, r, and s are distinct primes.
FORMULA
A000005(a(n))=40.
MATHEMATICA
Select[Range[20000], DivisorSigma[0, #]==40&] (* Vladimir Joseph Stephan Orlovsky, May 06 2011 *)
PROG
(PARI) is(n)=numdiv(n)==40 \\ Charles R Greathouse IV, Jun 19 2016
CROSSREFS
Sequence in context: A093787 A258920 A268288 * A231548 A179693 A290704
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Aug 27 2010
STATUS
approved