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A004742
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Numbers n such that binary expansion does not contain 101.
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9
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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;
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,3
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LINKS
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Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
Index entries for 2-automatic sequences.
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PROG
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(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
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CROSSREFS
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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
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane.
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STATUS
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approved
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