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