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 A307367 #22 May 06 2019 07:36:44
%S A307367 4,2,3,3,2,2,6,2,1,4,7,0,4,4,12,5,6,2,3,2,6,3,6,2,2,4,3,2,5,0,3,2,1,4,
%T A307367 3,1,10,1,4,0,3,2,2,1,1
%N A307367 Number of palindromic triangular numbers with exactly n digits.
%C A307367 Number of terms in A003098 with exactly n digits.
%C A307367 Differs from A054263 only at a(1), assuming 0 has 1 digits. - _R. J. Mathar_, May 06 2019
%H A307367 G. J. Simmons, <a href="/A002778/a002778_2.pdf">Palindromic powers</a>, J. Rec. Math., 3 (No. 2, 1970), 93-98. [Annotated scanned copy] See page 95.
%t A307367 A003098 = Select[PolygonalNumber[3, Range[0, 10^6]], PalindromeQ];
%t A307367 (* Set Range to level of desired running time. \ *)
%t A307367 Table[Length[ Select[A003098, IntegerLength[#] == n || (n == 1 && # == 0) &]], {n, 12}]
%t A307367 (* Set Range to encompass length of last value in A003098. *)
%Y A307367 Cf. A000217, A003098, A008509, A034822, A263618, A307348.
%K A307367 nonn,base,more
%O A307367 1,1
%A A307367 _Robert Price_, May 01 2019