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A003726 Numbers with no 3 adjacent 1's in binary expansion. 21
0, 1, 2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 32, 33, 34, 35, 36, 37, 38, 40, 41, 42, 43, 44, 45, 48, 49, 50, 51, 52, 53, 54, 64, 65, 66, 67, 68, 69, 70, 72, 73, 74, 75, 76, 77, 80, 81, 82 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

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

Index entries for 2-automatic sequences.

PROG

(Haskell)

a003726 n = a003726_list !! (n - 1)

a003726_list = filter f [0..] where

   f x = x < 7 || (x `mod` 8) < 7 && f (x `div` 2)

-- Reinhard Zumkeller, Jun 03 2012

(PARI) is(n)=!bitand(bitand(n, n<<1), n<<2) \\ Charles R Greathouse IV, Feb 11 2017

CROSSREFS

Cf. A063037; complement of A004781.

Cf. A007088; A003796 (no 000), A004745 (no 001), A004746 (no 010), A004744 (no 011), A003754 (no 100), A004742 (no 101), A004743 (no 110).

See A278038 for the binary representations of these numbers.

Sequence in context: A113619 A004765 A247063 * A004828 A032895 A032854

Adjacent sequences:  A003723 A003724 A003725 * A003727 A003728 A003729

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified October 21 13:05 EDT 2018. Contains 316422 sequences. (Running on oeis4.)