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 A008510 Both n and n-th triangular number are palindromes. 10
 1, 2, 3, 11, 77, 363, 1111, 2662, 111111, 246642, 11111111, 363474363, 2664444662, 26644444662, 246644446642, 266444444662, 2466444446642, 3654345456545434563 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES D. Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, 93. LINKS P. De Geest, Subsets of palindromic triangulars P. 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: A155187 A109132 A279084 * A290512 A042165 A089921 Adjacent sequences:  A008507 A008508 A008509 * A008511 A008512 A008513 KEYWORD nonn,base AUTHOR STATUS approved

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Last modified September 23 02:13 EDT 2018. Contains 315271 sequences. (Running on oeis4.)