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

Offset: 1

Author

Giovanni Resta, May 10 2006

Keywords

• nonn
• base
• more

Comments

Next term exceeds 1.4*10^16.

Links

• G. Resta, Tridigital Triangular Numbers

Crossrefs

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

Programs

Magma

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

Mathematica

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