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Numbers with exactly 4 distinct palindromic prime factors.
4

%I #14 Aug 14 2024 13:12:19

%S 210,330,462,770,1155,3030,3930,4242,4530,5430,5502,5730,6342,6666,

%T 7070,7602,8022,8646,9170,9390,9966,10570,10590,10605,11110,11190,

%U 11490,11946,12606,12670,13146,13370,13755,14410,14826,15554,15666,15855,16086,16610,16665

%N Numbers with exactly 4 distinct palindromic prime factors.

%H Andrew Howroyd, <a href="/A046402/b046402.txt">Table of n, a(n) for n = 1..1000</a>

%t Take[Times@@@Module[{nn=300,pp},pp=Select[Prime[Range[nn]],PalindromeQ];Subsets[pp,{4}]]//Union,40] (* _Harvey P. Dale_, Aug 13 2024 *)

%Y Intersection of A033620 and A046386.

%Y Cf. A046370.

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Jun 15 1998

%E Offset changed and a(37) onwards from _Andrew Howroyd_, Aug 14 2024