A386977 Products of 3 distinct semiprimes.

216, 240, 336, 360, 504, 528, 540, 560, 600, 624, 756, 792, 810, 816, 840, 880, 900, 912, 936, 1000, 1040, 1104, 1134, 1176, 1188, 1224, 1232, 1260, 1320, 1350, 1360, 1368, 1392, 1400, 1404, 1456, 1488, 1500, 1520, 1560, 1656, 1764, 1776, 1782, 1836, 1840, 1848

Offset: 1

Author

Ian Hahus, Aug 11 2025

Keywords

• nonn

Examples

			216 = 4 * 6 * 9.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001222, A001358 (semiprimes), A007304 (sphenic numbers).

Subsequence of A046306.

Programs

Maple

q:= n-> (l-> l=[3$2] or nops(l)>2 and add(i, i=l)=6)(ifactors(n)[2][..., 2]):
select(q, [$1..2000])[];  # Alois P. Heinz, Aug 12 2025

Mathematica

Select[Range@ 2000, MemberQ[{{3,3}, {1,1,4}, {1,2,3}, {2,2,2}, {1,1,1,3}, {1,1,2,2}, {1,1,1,1,2}, {1,1,1,1,1,1}}, Sort[Last /@ FactorInteger@ #]] &] (* Giovanni Resta, Aug 12 2025 *)