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 A118129 #13 Aug 13 2024 05:07:01 %S A118129 6,14,20,424,1042,8290,20802,21644,440512,548008,749171,4366390, %T A118129 5378548,9850174,17930596,36158854,130427194,407305710,3077094752, %U A118129 93416875260 %N A118129 Numbers k such that the sum of the first k odd composites is palindromic in base 3. %C A118129 No more terms through 10^9. %C A118129 Any subsequent terms are > 10^11. - _Lucas A. Brown_, Aug 12 2024 %H A118129 Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/A118129.py">Python program</a>. %e A118129 The sum of the first 14 odd composites, when written in base 3, is the palindrome 201102, so 14 is in the sequence. %Y A118129 Cf. A058848 (palindromic in base 10). %K A118129 nonn,base,hard,more %O A118129 1,1 %A A118129 _Ryan Propper_, May 12 2006 %E A118129 a(19)-a(20) from _Lucas A. Brown_, Aug 12 2024