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A307348 Numbers k such that there are no palindromic triangular numbers of length k. 2
12, 30, 40 (list; graph; refs; listen; history; text; internal format)
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, A08509, 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

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Last modified July 11 20:03 EDT 2020. Contains 335652 sequences. (Running on oeis4.)