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

12, 30, 40

Offset

1,1

Links

Table of n, a(n) for n=1..3.

P. De Geest, Palindromic Squares

Eric Weisstein's World of Mathematics, Palindromic Number

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. *)

Crossrefs

Cf. A000217, A003098, A008509, A034822.

Sequence in context: A329947 A115912 A083096 * A289691 A145469 A024364

Adjacent sequences: A307345 A307346 A307347 * A307349 A307350 A307351

Keyword

nonn,base,hard,more

Author

Robert Price, May 01 2019

Status

approved