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 A333423 #22 Jun 28 2023 12:37:08 %S A333423 0,1,3,7,9,11,31,39,47,211,217,223,229,235,243,249,255,261,267,275, %T A333423 281,287,293,299,2311,2347,2383,2419,2455,2523,2559,2595,2631,2667, %U A333423 2735,2771,2807,2843,2879,30031,30061,30091,30121,30151,30181,30211,30247,30277,30307 %N A333423 Numbers that are palindromes in primorial base. %H A333423 Amiram Eldar, <a href="/A333423/b333423.txt">Table of n, a(n) for n = 1..2500</a> %H A333423 Wikipedia, <a href="https://en.wikipedia.org/wiki/Mixed_radix#Primorial_number_system">Primorial number system</a>. %H A333423 <a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a>. %e A333423 3 is a term since its representation in primorial base is 11 (1 * 2# + 1) which is a palindrome. %e A333423 7 is a term since its representation in primorial base is 101 (1 * 3# + 0 * 2# + 1 = 6 + 1) which is a palindrome. %t A333423 max = 6; bases = Prime @ Range[max, 1, -1]; nmax = Times @@ bases - 1; Select[Range[0, nmax], PalindromeQ @ IntegerDigits[#, MixedRadix[bases]] &] %Y A333423 Cf. A049345, A235168. %Y A333423 Cf. A002113, A006995, A014190, A014192, A029952, A029953, A029954, A029803, A029955, A046807. %K A333423 nonn,base %O A333423 1,3 %A A333423 _Amiram Eldar_, Mar 20 2020