A119042 - OEIS

A119042

Numbers k such that the k-th triangular number contains only digits {0,1,6}.

1, 3, 4, 11, 36, 141, 179, 363, 1095, 3633, 4473, 4704, 36333, 44758, 46079, 46904, 57620, 1414920, 1460141, 4474371, 14560288, 348310541, 1822424761720, 34670191840011, 471172177895936, 4472359691719799

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OFFSET

1,2

COMMENTS

Next term exceeds 1.4*10^16.

LINKS

Table of n, a(n) for n=1..26.

G. Resta, Tridigital Triangular Numbers

MATHEMATICA

Select[Range[2 10^7], Complement[IntegerDigits[Binomial[# + 1, 2]], {0, 1, 6}] == {} &] (* Vincenzo Librandi, Dec 25 2015 *)

PROG

(Magma) [n: n in [1..2*10^7] | Set(Intseq(Binomial(n+1, 2))) subset [0, 1, 6]]; // Vincenzo Librandi, Dec 25 2015

CROSSREFS

Cf. A000217, A119041. See A119034 for a table of cross-references.

Sequence in context: A242044 A344263 A275309 * A042273 A179167 A259845

Adjacent sequences: A119039 A119040 A119041 * A119043 A119044 A119045

KEYWORD

nonn,base,more

AUTHOR

Giovanni Resta, May 10 2006

STATUS

approved