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 A145733 #7 Jun 02 2025 00:40:47 %S A145733 1,2,3,4,6,9,10,11,12,16,18 %N A145733 Indices of palindromes in A001127. %C A145733 The next term (if it exists) is greater than 10000. %C A145733 These are actually indices into A001127 right-shifted; A001127 has offset 0, but this sequence treats it as having offset 1. %e A145733 The 9th term in A001127 is 1111, which is a palindrome, thus 9 is in the sequence. %Y A145733 A001127 %K A145733 nonn,base %O A145733 1,2 %A A145733 _Dmitry Kamenetsky_, Oct 17 2008