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A119146
Triangular numbers composed of digits {1,7,8}.
2
1, 78, 171, 1711, 8778, 11781, 887778, 1188111, 18111171, 71778171, 88877778, 811178781, 7781717881, 8888777778, 181877771881, 887788118778, 888887777778, 88877878118778, 88888877777778, 181887881178871, 8888778778118778, 8888888777777778, 117888788817817111
OFFSET
1,2
FORMULA
a(n) = A000217(A119147(n)). - Tyler Busby, Mar 31 2023
CROSSREFS
Cf. A000217, A053913, A119147. See A119033 for a table of cross-references.
Sequence in context: A044329 A044710 A046428 * A044410 A044791 A232386
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, May 10 2006
EXTENSIONS
a(21)-a(23) from Tyler Busby, Mar 22 2023
STATUS
approved