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A004742 Numbers n such that binary expansion does not contain 101. 9
0, 1, 2, 3, 4, 6, 7, 8, 9, 12, 14, 15, 16, 17, 18, 19, 24, 25, 28, 30, 31, 32, 33, 34, 35, 36, 38, 39, 48, 49, 50, 51, 56, 57, 60, 62, 63, 64, 65, 66, 67, 68, 70, 71, 72, 73, 76, 78, 79, 96, 97, 98, 99, 100, 102, 103, 112, 113, 114, 115, 120, 121, 124, 126, 127 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Index entries for 2-automatic sequences.

PROG

(PARI) is(n)=n=binary(n); for(i=3, #n, if(n[i]&&n[i-2]&&!n[i-1], return(0))); 1 \\ Charles R Greathouse IV, Mar 26 2013

(PARI) is(n)=while(n>4, if(bitand(n, 7)==5, return(0)); n>>=1); 1 \\ Charles R Greathouse IV, Feb 11 2017

(Haskell)

a004742 n = a004742_list !! (n-1)

a004742_list = filter f [0..] where

   f x  = x < 4 || x `mod` 8 /= 5 && f (x `div` 2)

-- Reinhard Zumkeller, Jul 01 2013

CROSSREFS

Cf. A007088; A003796 (no 000), A004745 (no 001), A004746 (no 010), A004744 (no 011), A003754 (no 100), A004743 (no 110), A003726 (no 111).

Sequence in context: A023747 A031998 A023759 * A277817 A100290 A140181

Adjacent sequences:  A004739 A004740 A004741 * A004743 A004744 A004745

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified October 13 18:57 EDT 2019. Contains 327981 sequences. (Running on oeis4.)