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A008510
Numbers k such that both k and the k-th triangular number are palindromes.
11
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.
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
KEYWORD
nonn,base,more
STATUS
approved