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

1,1

Links

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

Example

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

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 *)

Crossrefs

Cf. A002182.

Sequence in context: A297568 A353795 A317518 * A071228 A304077 A108997

Adjacent sequences: A307760 A307761 A307762 * A307764 A307765 A307766

Keyword

nonn

Author

Dmitry Kamenetsky, Apr 27 2019

Status

approved