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A119148
Triangular numbers composed of digits {1,7,9}.
2
1, 91, 171, 1711, 171991, 791911, 1717771191, 911977119991, 999999911791, 1771177919779971, 977779999771199191, 17979999719799917971, 7197199171171779119991779991
OFFSET
1,2
COMMENTS
a(14) > 10^40. - Tyler Busby, Mar 29 2023
FORMULA
a(n) = A000217(A119149(n)). - Tyler Busby, Mar 29 2023
CROSSREFS
Cf. A000217, A119149. See A119033 for a table of cross-references.
Sequence in context: A225908 A159961 A113530 * A166059 A226683 A370053
KEYWORD
nonn,base,more
AUTHOR
Giovanni Resta, May 10 2006
STATUS
approved