A119036 - OEIS

A119036

Numbers k such that the k-th triangular number contains only digits {0,1,3}.

1, 2, 4, 24, 77, 141, 778, 1421, 1435, 1620, 14220, 15035, 45453, 148533, 148546, 249122, 471404, 791597, 4497399, 2580747997, 47180737658, 148411814220, 244989930458, 447283652733, 1422190795997, 2581981034024

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OFFSET

1,2

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, 3}] == {}&] (* Vincenzo Librandi, Oct 07 2015 *)

Position[Accumulate[Range[300000]], _?(SubsetQ[{0, 1, 3}, IntegerDigits[#]]&)]//Quiet//Flatten (* The program generates the first 16 terms of the sequence. *) (* Harvey P. Dale, Nov 02 2025 *)

PROG

(Magma) [n: n in [1..2*10^7] | Set(Intseq(Binomial(n+1, 2))) subset [0, 1, 3]]; // Vincenzo Librandi, Oct 07 2015

CROSSREFS

Cf. A000217, A119035. See A119034 for a table of cross-references.

Sequence in context: A272640 A192513 A192384 * A192382 A232205 A170931

Adjacent sequences: A119033 A119034 A119035 * A119037 A119038 A119039

KEYWORD

nonn,base

AUTHOR

Giovanni Resta, May 10 2006

STATUS

approved