This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A075812 #13 Mar 10 2025 15:21:37 %S A075812 9,33,55,77,111,121,141,161,303,323,393,505,515,535,545,565,707,717, %T A075812 737,767,939,949,959,979,989,1111,1441,1661,1991,3113,3223,3443,3883, %U A075812 7117,7447,7997,9119,9229,9449,10001,10201,10401,10801,10901,11111 %N A075812 Palindromic odd numbers with exactly 2 prime factors (counted with multiplicity). %H A075812 Zak Seidov, <a href="/A075812/b075812.txt">Table of n, a(n) for n = 1..2000</a> %e A075812 9=3^2, 33=3*11 and 55=5*11 are palindromic, odd and are products of exactly 2 prime factors. %p A075812 test := proc(n) local d; d := convert(n,base,10); return ListTools[Reverse](d)=d and numtheory[bigomega](n)=2; end; a := []; for n from 1 to 14000 by 2 do if test(n) then a := [op(a),n]; end; od; a; %Y A075812 Cf. A046315. %Y A075812 Odd subsequence of A046328. %K A075812 nonn,base %O A075812 1,1 %A A075812 _Jani Melik_, Oct 13 2002 %E A075812 Edited by _Dean Hickerson_, Oct 21 2002