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 A068644 #7 Aug 11 2024 14:41:34 %S A068644 3,11,36,132,363,1287,3548,11088,18906,111111,417972,0,3707883, %T A068644 12812392,37009916,128127032,368505751,1014708805,3567632391, %U A068644 11151642876,36657342048,104561417190,417898160427,1325269593372 %N A068644 Index of the largest n-digit palindromic triangular number, or 0 if no such number exists. %H A068644 P. De Geest, <a href="https://www.worldofnumbers.com/em_alltria.htm">Exhaustive list of Palindromic Triangulars</a> %e A068644 a(4) = 132 as 132*133/2 = 8778 is the largest 4-digit palindromic triangular number. %e A068644 a(12) = 0 as no 12-digit palindromic triangular number exists. %Y A068644 Cf. A068641, A068642, A068643, A000217, A003098, A008509, A008510, A054263. %K A068644 base,nonn %O A068644 1,1 %A A068644 _Amarnath Murthy_, Feb 28 2002 %E A068644 Edited by _Patrick De Geest_, Mar 24 2002