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 A054263 #6 Aug 11 2024 14:41:32 %S A054263 3,2,3,3,2,2,6,2,1,4,7,0,4,4,12,5,6,2,3,2,6,3,6,2,2,4,3,2,5,0,3,2,1,4, %T A054263 3,1,10,1,4,0 %N A054263 Number of palindromic triangular numbers with n digits. %H A054263 P. De Geest, <a href="https://www.worldofnumbers.com/triangle.htm">Palindromic Triangulars</a> %e A054263 a(10) = 4: 1264114621, 1634004361, 5289009825, 6172882716. %Y A054263 Cf. A000217, A003098, A008509, A008510. %K A054263 nonn,base,hard %O A054263 1,1 %A A054263 _Patrick De Geest_, Apr 15 2000