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 A222726 #7 Jun 20 2025 16:36:12 %S A222726 33,303,323,333,343,363,393,3003,3113,3223,3333,3443,3553,3663,3773, %T A222726 3883,3993,30003,30303,30503,30603,30903,31213,31313,31413,31513, %U A222726 31613,31713,31813,31913,32023,32123,32223,32523,32623,32723,32823,32923,33033,33133,33233 %N A222726 Palindromic composite numbers starting with a digit 3. %C A222726 Subsequence of A032350 (palindromic nonprime numbers) and A002113 (palindromic numbers). Complement of A222725 (palindromic primes starting with a digit 3) with respect to A043038 (palindromic numbers starting with a digit 3). %H A222726 Jaroslav Krizek, <a href="/A222726/b222726.txt">Table of n, a(n) for n = 1..1021</a> %Y A222726 Cf. A032350, A002113, A222725, A043038. %K A222726 nonn,base %O A222726 1,1 %A A222726 _Jaroslav Krizek_, Mar 09 2013