A077813 Squarefree numbers containing in their decimal representation only the digits 0 and 1.

1, 10, 11, 101, 110, 111, 1001, 1010, 1011, 1101, 1110, 1111, 10001, 10010, 10011, 10101, 10110, 10111, 11001, 11010, 11101, 11110, 11111, 100001, 100010, 100011, 100101, 100110, 100111, 101001, 101010, 101011, 101101, 101110, 101111, 110001

Offset

1,2

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Example

a(51) = 1000110 = 2*3*5*17*37*53.

Mathematica

Union[Select[FromDigits/@Tuples[{1, 0}, 6], SquareFreeQ]] (* Harvey P. Dale, Nov 07 2013 *)

Prog

(Haskell)
a077813 n = a077813_list !! (n-1)
a077813_list = filter ((== 1) . a008966) $ tail $
   map ((foldr (\d v -> v * 10 + d) 0) . map fromIntegral) a030308_tabf
-- Reinhard Zumkeller, Nov 08 2013

Crossrefs

Cf. A077812, A020449, A005117.

Cf. A008966, A030308.

Sequence in context: A348109 A125099 A055611 * A203075 A104326 A205598

Adjacent sequences: A077810 A077811 A077812 * A077814 A077815 A077816

Keyword

nonn,base

Author

Reinhard Zumkeller, Nov 16 2002

Status

approved