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A109019 Numbers whose digit reversal is different and has the same number of prime factors (with multiplicity). 2

%I #20 Jun 03 2022 07:44:47

%S 13,15,17,26,31,37,39,49,51,58,62,71,73,79,85,93,94,97,107,113,115,

%T 117,122,123,126,129,143,147,149,155,157,158,159,165,167,169,177,178,

%U 179,183,185,187,199,203,205,221,225,226,244,246,265,270,285,286,289,290

%N Numbers whose digit reversal is different and has the same number of prime factors (with multiplicity).

%C _Ray Chandler_ has coauthorship credit for this sequence.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/AlmostPrime.html">Almost Prime</a>.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Emirp.html">Emirp</a>.

%H Eric Weisstein and Jonathan Vos Post, <a href="http://mathworld.wolfram.com/Emirpimes.html">Emirpimes.</a>

%F {A006567} U {A097393} U (A109023} U {A109024} U ... U {A109131} U ...

%t Select[Range@1000, ! PalindromeQ@# && Differences@PrimeOmega@{#,IntegerReverse@#} == {0} &] (* _Hans Rudolf Widmer_, Jun 03 2022 *)

%Y Cf. A006567, A097393, A109018, A109023-A109131.

%K nonn,base

%O 1,1

%A _Jonathan Vos Post_, Jun 16 2005

%E More terms from _Stefan Steinerberger_, Jun 16 2007

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Last modified July 19 18:18 EDT 2024. Contains 374410 sequences. (Running on oeis4.)