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A278569 Numbers of the form p^i*q^j*r^k where p,q,r are distinct odd primes and i,j,k >= 1. 3

%I #11 Dec 05 2016 08:39:06

%S 105,165,195,231,255,273,285,315,345,357,385,399,429,435,455,465,483,

%T 495,525,555,561,585,595,609,615,627,645,651,663,665,693,705,715,735,

%U 741,759,765,777,795,805,819,825,855,861,885,897,903,915,935,945,957,969,975,987,1001,1005,1015,1023,1035,1045,1065,1071,1085,1095,1105,1113,1131,1173,1185,1197,1209

%N Numbers of the form p^i*q^j*r^k where p,q,r are distinct odd primes and i,j,k >= 1.

%C More than the usual number of terms are included to show the difference from A216918 (the latter includes 3*5*7*11 = 1155 and all terms of A046390, A046391 etc).

%C If i,j,k are all equal to 1 we get A046389.

%H Michael De Vlieger, <a href="/A278569/b278569.txt">Table of n, a(n) for n = 1..10000</a>

%F A033992 INTERSECT A005408. - _R. J. Mathar_, Dec 05 2016

%t Select[Range@ 1500, PrimeNu@ # == 3 && OddQ@ # &] (* _Michael De Vlieger_, Dec 05 2016 *)

%Y Includes A046389, subsequence of A216918.

%K nonn

%O 1,1

%A _N. J. A. Sloane_, Nov 27 2016

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Last modified March 28 08:12 EDT 2024. Contains 371236 sequences. (Running on oeis4.)