A307763 Highly composite numbers that are a product of two highly composite numbers greater than 1.

4, 12, 24, 36, 48, 120, 240, 360, 720, 1680, 2520, 5040, 7560, 10080, 15120, 20160, 45360, 50400, 55440, 110880, 166320, 221760, 332640, 498960, 554400, 665280, 1441440, 2162160, 2882880, 4324320, 6486480, 7207200, 8648640, 14414400, 17297280, 21621600, 43243200, 73513440

Offset: 1

Author

Dmitry Kamenetsky, Apr 27 2019

Keywords

• nonn

Examples

			7560 = 6 * 1260. 6 and 1260 are both highly composite numbers, so 7560 is in the sequence.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A002182.

Programs

Mathematica

hcQ[n_, v_] := AnyTrue[v, MemberQ[v, n/#] &]; hc = {}; s = {}; dm = 0; Do[d = DivisorSigma[0, n]; If[d > dm, dm = d; If[hcQ[n, hc], AppendTo[s, n]]; AppendTo[hc, n]], {n, 10^7}]; s (* Amiram Eldar, Jul 05 2019 *)