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A119170 Triangular numbers composed of digits {2,5,9}. 2
55, 595, 5995, 255255, 292995, 299925, 25952229225, 99292929555225, 55955525255559595, 555959229929999252295, 925952955522559552259925, 5299552922255552929595999295, 5995959559225555222929295255522595295, 9925559955529295222599225259529552225 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
a(15) > 10^40. - Tyler Busby, Mar 24 2023
LINKS
FORMULA
a(n) = A000217(A119171(n)).
a(n) == 5 (mod 10) for all n. - Chai Wah Wu, Nov 30 2018
MATHEMATICA
Flatten[Table[Select[FromDigits /@ Tuples[{2, 5, 9}, n], IntegerQ[(Sqrt[8 # + 1] - 1)/2] &], {n, 11}]] (* Amiram Eldar, Nov 30 2018 *)
CROSSREFS
Cf. A000217, A053929, A119171. See A119033 for a table of cross-references.
Sequence in context: A222797 A180326 A119085 * A119228 A119226 A219928
KEYWORD
nonn,base,more
AUTHOR
Giovanni Resta, May 10 2006
EXTENSIONS
a(13)-a(14) from Tyler Busby, Mar 24 2023
STATUS
approved

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Last modified August 31 19:25 EDT 2024. Contains 375573 sequences. (Running on oeis4.)