A119038 Numbers k such that the k-th triangular number contains only digits {0,1,4}.

1, 4, 141, 144, 286, 9055, 16795, 44944, 90598, 167579, 15100424, 29678424, 45637726, 283245880, 5291767266, 1442505046119, 45042455839799, 151069595909375, 14429213707617199, 90999011435291333

Offset

1,2

Comments

Next term must be greater than 4.4*10^18.

Links

Table of n, a(n) for n=1..20.

G. Resta, Tridigital Triangular Numbers

Mathematica

Select[Range[2 10^7], Complement[IntegerDigits[Binomial[# + 1, 2]], {0, 1, 4}] == {}&] (* Vincenzo Librandi, Oct 07 2015 *)

Prog

(Magma) [n: n in [1..2*10^7] | Set(Intseq(Binomial(n+1, 2))) subset [0, 1, 4]]; // Vincenzo Librandi, Oct 07 2015

Crossrefs

Cf. A000217, A119037. See A119034 for a table of cross-references.

Sequence in context: A235536 A229453 A215606 * A048432 A332114 A262653

Adjacent sequences: A119035 A119036 A119037 * A119039 A119040 A119041

Keyword

nonn,base

Author

Giovanni Resta, May 10 2006

Extensions

Two more terms from Max Alekseyev, Jul 11 2009

Status

approved