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 A045914 Triangular numbers with all digits the same. 14
 0, 1, 3, 6, 55, 66, 666 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS A118668(a(n)) = 1. - Reinhard Zumkeller, Jul 11 2015 REFERENCES D. Ballew and R. Weger, Repdigit triangular numbers, J. Rec. Math. Vol. 8(2), p. 96, 1975-76. L. E. Dickson, History of the Theory of Numbers, Vol. II, p. 33, Chelsea NY, 1952. E. B. Escott, Math. Quest. Educational Times, (2) 8 (1905), 33-34. - N. J. A. Sloane, Mar 31 2014 Bir Kafle et al., Triangular repblocks, Fib. Q., 56:4 (2018), 325-328. LINKS MATHEMATICA Select[Union[Flatten[Table[FromDigits[PadRight[{}, n, k]], {n, 3}, {k, 0, 9}]]], OddQ[ Sqrt[8#+1]]&] (* Harvey P. Dale, Feb 11 2020 *) CROSSREFS Cf. A213516 (triangular numbers having only 1 or 2 different digits). Cf. A118668. Sequence in context: A066569 A051641 A003098 * A303351 A067610 A067609 Adjacent sequences:  A045911 A045912 A045913 * A045915 A045916 A045917 KEYWORD fini,full,nonn,base AUTHOR EXTENSIONS Added 0 - T. D. Noe, Jun 22 2012 STATUS approved

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Last modified December 2 14:26 EST 2020. Contains 338877 sequences. (Running on oeis4.)