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A119039
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Triangular numbers composed of digits {0,1,5}.
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2
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1, 10, 15, 55, 105, 5050, 5151, 10011, 15051, 105111, 500500, 501501, 505515, 510555, 10015050, 50005000, 50015001, 50055015, 50105055, 51010050, 51111105, 51151555, 110551015, 1051501011, 1505550501, 5000050000, 5000150001, 5000550015, 5001050055, 5010055050
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OFFSET
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1,2
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LINKS
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Table of n, a(n) for n=1..30.
G. Resta, Tridigital Triangular Numbers
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MATHEMATICA
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Rest[Select[FromDigits/@Tuples[{0, 1, 5}, 12], IntegerQ[(Sqrt[8 # + 1] - 1)/2] &]] (* Vincenzo Librandi, Dec 18 2015 *)
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PROG
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(Magma) [t: n in [1..2*10^7] | Set(Intseq(t)) subset {0, 1, 5} where t is n*(n+1) div 2]; // Vincenzo Librandi, Dec 18 2015
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CROSSREFS
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Cf. A000217, A058416, A119040. See A119033 for a table of cross-references.
Sequence in context: A330203 A272307 A092192 * A047189 A278921 A035407
Adjacent sequences: A119036 A119037 A119038 * A119040 A119041 A119042
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KEYWORD
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nonn,base
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AUTHOR
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Giovanni Resta, May 10 2006
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EXTENSIONS
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More terms from Vincenzo Librandi, Dec 18 2015
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STATUS
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approved
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