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A307763 Highly composite numbers that are a product of two highly composite numbers greater than 1. 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 (list; graph; refs; listen; history; text; internal format)
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: A218391 A297568 A317518 * A071228 A304077 A108997

Adjacent sequences:  A307760 A307761 A307762 * A307764 A307765 A307766

KEYWORD

nonn

AUTHOR

Dmitry Kamenetsky, Apr 27 2019

STATUS

approved

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Last modified July 10 12:34 EDT 2020. Contains 335576 sequences. (Running on oeis4.)