A008510 Numbers k such that both k and the k-th triangular number are palindromes.

1, 2, 3, 11, 77, 363, 1111, 2662, 111111, 246642, 11111111, 363474363, 2664444662, 26644444662, 246644446642, 266444444662, 2466444446642, 3654345456545434563

Offset

1,2

References

D. Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, 93.

Links

Table of n, a(n) for n=1..18.

Patrick De Geest, Subsets of palindromic triangulars

Patrick De Geest, For the last term

Mathematica

palQ[n_] := Reverse[x = IntegerDigits[n]] == x; t = {}; Do[If[palQ[n] && palQ[n*(n + 1)/2], AppendTo[t, n]], {n, 1.2*10^7}]; t (* Jayanta Basu, May 15 2013 *)

Crossrefs

Sequence in context: A338613 A109132 A279084 * A290512 A042165 A089921

Adjacent sequences: A008507 A008508 A008509 * A008511 A008512 A008513

Keyword

nonn,base,more

Author

Patrick De Geest

Status

approved