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A119216 Triangular numbers composed of digits {4,7,8}. 2
78, 8778, 448878, 887778, 7478778, 88877778, 8888777778, 44847878778, 747488474778, 888887777778, 88888877777778, 8888888777777778, 888888887777777778, 7778777484477877878, 88888888877777777778 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..15.

G. Resta, Tridigital Triangular Numbers

MATHEMATICA

Table[Select[FromDigits/@Tuples[{4, 7, 8}, n], OddQ[Sqrt[8#+1]]&], {n, 20}]//Flatten (* The program will take a long time to run. *) (* Harvey P. Dale, Oct 15 2017 *)

CROSSREFS

Cf. A000217, A053963, A119217. See A119033 for a table of cross-references.

Sequence in context: A268023 A268016 A077694 * A119236 A126998 A299712

Adjacent sequences: A119213 A119214 A119215 * A119217 A119218 A119219

KEYWORD

nonn,base

AUTHOR

Giovanni Resta, May 10 2006

STATUS

approved

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Last modified February 4 14:20 EST 2023. Contains 360055 sequences. (Running on oeis4.)