A119035 - OEIS

A119035

Triangular numbers composed of digits {0,1,3}.

1, 3, 10, 300, 3003, 10011, 303031, 1010331, 1030330, 1313010, 101111310, 113033130, 1033010331, 11031100311, 11033031331, 31031010003, 111111101310, 313313301003, 10113301131300, 3330130113300130003, 1113011003000100031311, 11013033300110103011310

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..22.

Giovanni Resta, Tridigital Triangular Numbers.

FORMULA

a(n) = A000217(A119036(n)). - Tyler Busby, Mar 31 2023

MATHEMATICA

Rest[Select[FromDigits/@Tuples[{0, 1, 3}, 10], IntegerQ[(Sqrt[8 # + 1] - 1)/2] &]] (* Vincenzo Librandi, Dec 18 2015 *)

PROG

(Magma) [t: n in [1..2*10^7] | Set(Intseq(t)) subset {0, 1, 3} where t is n*(n+1) div 2]; // Vincenzo Librandi, Dec 18 2015

CROSSREFS

Cf. A000217, A119036. See A119033 for a table of cross-references.

Sequence in context: A270553 A308657 A156193 * A359554 A004100 A349894

Adjacent sequences: A119032 A119033 A119034 * A119036 A119037 A119038

KEYWORD

nonn,base

AUTHOR

Giovanni Resta, May 10 2006

EXTENSIONS

a(21)-a(22) from Tyler Busby, Mar 22 2023

STATUS

approved