

A307367


Number of palindromic triangular numbers with exactly n digits.


1



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, 3, 1, 10, 1, 4, 0, 3, 2, 2, 1, 1
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OFFSET

1,1


COMMENTS

Number of terms in A003098 with exactly n digits.
Differs from A054263 only at a(1), assuming 0 has 1 digits.  R. J. Mathar, May 06 2019


LINKS

Table of n, a(n) for n=1..45.
G. J. Simmons, Palindromic powers, J. Rec. Math., 3 (No. 2, 1970), 9398. [Annotated scanned copy] See page 95.


MATHEMATICA

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


CROSSREFS

Cf. A000217, A003098, A008509, A034822, A263618, A307348.
Sequence in context: A073244 A106644 A190874 * A136626 A079623 A177864
Adjacent sequences: A307364 A307365 A307366 * A307368 A307369 A307370


KEYWORD

nonn,base,more


AUTHOR

Robert Price, May 01 2019


STATUS

approved



