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 A068643 #7 Aug 11 2024 14:41:34 %S A068643 6,66,666,8778,66066,828828,6295926,61477416,178727871,6172882716, %T A068643 87350505378,0,68742000024786,82078700787028,684866959668486, %U A068643 8208268228628028,67898244444289876,514816979979618415 %N A068643 Largest n-digit palindromic triangular number, or 0 if no such number exists. %H A068643 P. De Geest, <a href="https://www.worldofnumbers.com/em_alltria.htm">Exhaustive list of Palindromic Triangulars</a> %e A068643 a(4) = 8778 = 132*133/2 is the largest 4-digit palindromic triangular number. %e A068643 a(12) = 0 as no 12-digit palindromic triangular number exists. %Y A068643 Cf. A068641, A068642, A068644, A000217, A003098, A008509, A008510, A054263. %K A068643 base,nonn %O A068643 1,1 %A A068643 _Amarnath Murthy_, Feb 28 2002 %E A068643 Edited by _Patrick De Geest_, Mar 24 2002