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A075800 Palindromic numbers which are products of an odd number of distinct primes. 1

%I #9 Mar 29 2016 04:22:03

%S 2,3,5,7,11,66,101,131,151,181,191,222,282,313,353,373,383,434,474,

%T 494,555,595,606,646,727,757,777,787,797,919,929,969,1001,1221,1551,

%U 1771,2222,2882,3333,3553,4334,4994,5335,5555,5665,5885,5995,6006,6226,6446

%N Palindromic numbers which are products of an odd number of distinct primes.

%H Chai Wah Wu, <a href="/A075800/b075800.txt">Table of n, a(n) for n = 1..10000</a>

%e 191 is palindromic and prime, 222=2*3*37 is palindromic and a product of 3 distinct primes.

%p test := proc(n) local d; d := convert(n,base,10); return ListTools[Reverse](d)=d and numtheory[mobius](n)=-1; end; a := []; for n from 1 to 7000 do if test(n) then a := [op(a),n]; end; od; a;

%Y Cf. A002385, A069217, A032350, A030059.

%K nonn,base

%O 1,1

%A _Jani Melik_, Oct 13 2002

%E Edited by _Dean Hickerson_, Oct 21 2002

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Last modified March 28 15:38 EDT 2024. Contains 371254 sequences. (Running on oeis4.)