A307348 Numbers k such that there are no palindromic triangular numbers of length k.

12, 30, 40

Offset: 1

Author

Robert Price, May 01 2019

Keywords

• nonn
• base
• hard
• more

Links

• Patrick De Geest, Palindromic Squares in bases 2 to 17
• Eric Weisstein's World of Mathematics, Palindromic Number

Crossrefs

Cf. A000217, A003098, A008509, A034822.

Programs

Mathematica

A003098 = Select[PolygonalNumber[3, Range[0, 10^6]], PalindromeQ];
(* Set Range to level of desired running time. *)
nopal[n_] := Length[Select[A003098, IntegerLength[#] == n || (n == 1 && # == 0) &]]; Select[Range[12], nopal[#] == 0 &]
(* Set Range to encompass length of last value in A003098. *)