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A119103
Triangular numbers composed of digits {1,2,6}.
2
1, 6, 21, 66, 666, 2211, 6216, 212226, 222111, 1222266, 1261666, 16626261, 22121226, 22221111, 121111266, 126222216, 661261161, 2162616261, 2221211226, 2222211111, 21166222626, 66126661611, 166122226621, 216262612611, 222212111226, 222222111111, 22162261612611
OFFSET
1,2
FORMULA
a(n) = A000217(A119104(n)). - Michel Marcus, Mar 16 2023
MATHEMATICA
Flatten[Table[Select[FromDigits/@Tuples[{1, 2, 6}, n], OddQ[Sqrt[8#+1]]&], {n, 12}]] (* Harvey P. Dale, Mar 07 2015 *)
CROSSREFS
Cf. A000217, A053883, A119104. See A119033 for a table of cross-references.
Sequence in context: A117962 A105457 A134931 * A180795 A306089 A107653
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, May 10 2006
EXTENSIONS
a(24)-a(27) from Tyler Busby, Mar 14 2023
STATUS
approved