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A004781 Binary expansion contains 3 adjacent 1's. 6
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)
OFFSET
1,1
LINKS
FORMULA
a(n) ~ n. - Charles R Greathouse IV, Sep 24 2012
MAPLE
q:= n-> verify([1$3], Bits[Split](n), 'sublist'):
select(q, [$0..200])[]; # Alois P. Heinz, Oct 22 2021
MATHEMATICA
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 *)
PROG
(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)
-- Reinhard Zumkeller, Jun 03 2012
(PARI) is(n)=!!bitand(bitand(n, n<<1), n<<2) \\ Charles R Greathouse IV, Sep 24 2012
CROSSREFS
Complement of A003726.
Sequence in context: A085335 A069137 A141164 * A004759 A364287 A062056
KEYWORD
nonn,base,easy
AUTHOR
EXTENSIONS
Offset corrected by Reinhard Zumkeller, Jun 03 2012
STATUS
approved

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Last modified April 16 17:36 EDT 2024. Contains 371749 sequences. (Running on oeis4.)