A046754 Numbers k such that the square of d(k) (number of divisors) divides k.

1, 9, 128, 625, 972, 1152, 2000, 2025, 5625, 6561, 7776, 8100, 10000, 10800, 18000, 21952, 26244, 30000, 32768, 35721, 50625, 55296, 56700, 64000, 64800, 65856, 70000, 80000, 84672, 89100, 90000, 97200, 98304, 99225, 105300, 109760, 110000

Offset: 1

Author

Labos Elemer

Keywords

• nonn

Comments

Subset of A033950.

Examples

			If k = 972, d(k) = sigma(0,k) = 18. Its square is 324 which divides 972.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Donovan Johnson)

Crossrefs

Cf. A033950, A046755, A046756.

Programs

Mathematica

Select[Range[110000], IntegerQ[#/DivisorSigma[0, #]^2] &] (* Jayanta Basu, Jun 28 2013 *)