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 A119035 Triangular numbers composed of digits {0,1,3}. 2
 1, 3, 10, 300, 3003, 10011, 303031, 1010331, 1030330, 1313010, 101111310, 113033130, 1033010331, 11031100311, 11033031331, 31031010003, 111111101310, 313313301003, 10113301131300, 3330130113300130003, 1113011003000100031311, 11013033300110103011310 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Giovanni Resta, Tridigital Triangular Numbers. FORMULA a(n) = A000217(A119036(n)). - Tyler Busby, Mar 31 2023 MATHEMATICA Rest[Select[FromDigits/@Tuples[{0, 1, 3}, 10], IntegerQ[(Sqrt[8 # + 1] - 1)/2] &]] (* Vincenzo Librandi, Dec 18 2015 *) PROG (Magma) [t: n in [1..2*10^7] | Set(Intseq(t)) subset {0, 1, 3} where t is n*(n+1) div 2]; // Vincenzo Librandi, Dec 18 2015 CROSSREFS Cf. A000217, A119036. See A119033 for a table of cross-references. Sequence in context: A270553 A308657 A156193 * A359554 A004100 A349894 Adjacent sequences: A119032 A119033 A119034 * A119036 A119037 A119038 KEYWORD nonn,base,changed AUTHOR Giovanni Resta, May 10 2006 EXTENSIONS a(21)-a(22) from Tyler Busby, Mar 22 2023 STATUS approved

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Last modified April 1 22:19 EDT 2023. Contains 361716 sequences. (Running on oeis4.)