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A119125
Triangular numbers composed of digits {1,4,6}.
2
1, 6, 66, 666, 6441, 41616, 146611, 464166, 1464616, 4114146, 14116641, 664611111, 1164441411, 16646464416, 41641661166, 66114661161, 144161141446, 161646441166, 1464464661166, 4464411144441, 44416146616416, 61116114144646, 466141616644641, 1116644466666141, 1161666441164166
OFFSET
1,2
FORMULA
a(n) = A000217(A119126(n)). - Michel Marcus, Mar 22 2023
MATHEMATICA
Table[Select[FromDigits/@Tuples[{1, 4, 6}, n], OddQ[Sqrt[8#+1]]&], {n, 16}]//Flatten (* Harvey P. Dale, Jun 20 2023 *)
CROSSREFS
Cf. A000217, A027676, A119126. See A119033 for a table of cross-references.
Sequence in context: A119100 A119176 A155630 * A137120 A002280 A073548
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, May 10 2006
EXTENSIONS
a(22)-a(24) from Tyler Busby, Mar 22 2023
a(25) from Harvey P. Dale, Jun 20 2023
STATUS
approved