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A119134 Triangular numbers composed of digits {1,5,7}. 2
1, 15, 55, 171, 1711, 5151, 11175, 551775, 1777555, 17555775, 51151555, 115117551, 1115171151, 151577151715, 171115717515, 551171777775, 1175175575155, 1577775175717755, 5511171777517575, 7571117555155155, 517577151571517115, 757171775575551115 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
a(n) = A000217(A119135(n)). - Tyler Busby, Mar 31 2023
CROSSREFS
Cf. A000217, A119135. See A119033 for a table of cross-references.
Sequence in context: A062025 A211797 A172436 * A119658 A072745 A141839
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, May 10 2006
EXTENSIONS
a(21)-a(22) from Tyler Busby, Mar 23 2023
STATUS
approved

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Last modified June 13 22:21 EDT 2024. Contains 373391 sequences. (Running on oeis4.)