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 A119208 Triangular numbers composed of digits {4,5,9}. 2
 45, 55, 595, 5995, 49455, 55945, 594595, 5559445, 555594445, 9955945495, 55555944445, 95444955595, 5555559444445, 9545454599955, 499594959455595, 549999555454495, 555555594444445, 55555555944444445, 5555555559444444445, 5999995494459499455 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..20. Giovanni Resta, Tridigital Triangular Numbers. FORMULA a(n) = A000217(A119209(n)). - Tyler Busby, Mar 25 2023 MATHEMATICA Select[Flatten[Table[FromDigits/@Tuples[{4, 5, 9}, n], {n, 17}]], OddQ[ Sqrt[ 8#+1]]&] (* The program will take a long time to run. *) (* Harvey P. Dale, May 23 2021 *) CROSSREFS Cf. A000217, A053955, A119209. See A119033 for a table of cross-references. Sequence in context: A116247 A168108 A037042 * A068812 A119071 A119158 Adjacent sequences: A119205 A119206 A119207 * A119209 A119210 A119211 KEYWORD nonn,base AUTHOR Giovanni Resta, May 10 2006 EXTENSIONS a(19)-a(20) from Tyler Busby, Mar 25 2023 STATUS approved

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Last modified June 5 16:06 EDT 2023. Contains 363137 sequences. (Running on oeis4.)