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Numbers with exactly 6 semiprime divisors.
5

%I #11 Dec 28 2021 14:50:57

%S 210,330,390,462,510,546,570,690,714,770,798,858,870,900,910,930,966,

%T 1110,1122,1155,1190,1218,1230,1254,1290,1302,1326,1330,1365,1410,

%U 1430,1482,1518,1554,1590,1610,1722,1764,1770,1785,1794,1800,1806,1830,1870,1914,1938,1974,1995

%N Numbers with exactly 6 semiprime divisors.

%t q[n_] := DivisorSum[n, 1 &, PrimeOmega[#] == 2 &] == 6; Select[Range[2000], q] (* _Amiram Eldar_, Dec 28 2021 *)

%o (PARI) isok(k) = sumdiv(k, d, bigomega(d)==2) == 6; \\ _Michel Marcus_, Dec 28 2021

%Y Numbers with exactly k semiprime divisors: A346041 (k=1), A345381 (k=2), A345382 (k=3), A350371 (k=4), A350372 (k=5), this sequence (k=6), A350374 (k=7), A350375 (k=8).

%K nonn

%O 1,1

%A _Wesley Ivan Hurt_, Dec 27 2021