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 A068642 #9 Aug 11 2024 14:41:34 %S A068642 1,10,18,77,173,1111,1593,8382,18906,50281,167053,0,1620621,6307938, %T A068642 15126258,50008881,149142458,846122222,2480116437,5513600773, %U A068642 14667896198,49786655918,246644446642,529670494286,2466444446642 %N A068642 Index of the smallest n-digit palindromic triangular number, or 0 if no such number exists. %H A068642 P. De Geest, <a href="https://www.worldofnumbers.com/em_alltria.htm">Exhaustive list of Palindromic Triangulars</a> %e A068642 a(4) = 77 as 77*78/2 = 3003 is the smallest 4-digit palindromic triangular number. %e A068642 a(12) = 0 as no 12-digit palindromic triangular number exists. %Y A068642 Cf. A068641, A068643, A068644, A000217, A003098, A008509, A008510, A054263. %K A068642 base,nonn %O A068642 1,2 %A A068642 _Amarnath Murthy_, Feb 28 2002 %E A068642 Edited by _Patrick De Geest_, Mar 24 2002