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A004781
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Binary expansion contains 3 adjacent 1's.
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6
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7, 14, 15, 23, 28, 29, 30, 31, 39, 46, 47, 55, 56, 57, 58, 59, 60, 61, 62, 63, 71, 78, 79, 87, 92, 93, 94, 95, 103, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 135, 142, 143, 151, 156, 157, 158, 159, 167
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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LINKS
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FORMULA
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MAPLE
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q:= n-> verify([1$3], Bits[Split](n), 'sublist'):
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MATHEMATICA
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Select[Range[200], MemberQ[Partition[IntegerDigits[#, 2], 3, 1], {1, 1, 1}]&] (* Harvey P. Dale, Mar 31 2011 *)
Select[Range[200], StringContainsQ[IntegerString[#, 2], "111"] &] (* Amiram Eldar, Oct 22 2021 *)
Select[Range[200], SequenceCount[IntegerDigits[#, 2], {1, 1, 1}]>0&] (* Harvey P. Dale, Dec 28 2021 *)
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PROG
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(Haskell)
a004781 n = a004781_list !! (n - 1)
a004781_list = filter f [0..] where
f x | x < 7 = False
| otherwise = (x `mod` 8) == 7 || f (x `div` 2)
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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