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A370427 a(n) is the least k >= 0 such that n OR k is a binary palindrome (where OR denotes the bitwise OR operator). 2
0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 5, 4, 3, 2, 1, 0, 1, 0, 9, 8, 1, 0, 9, 8, 3, 2, 1, 0, 3, 2, 1, 0, 1, 0, 17, 16, 9, 8, 25, 24, 5, 4, 21, 20, 1, 0, 17, 16, 3, 2, 1, 0, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 0, 33, 32, 17, 16, 49, 48, 1, 0, 33, 32, 17, 16, 49, 48 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,11
COMMENTS
The binary expansions of n and a(n) have no common 1's.
LINKS
FORMULA
n AND a(n) = 0 (where AND denotes the bitwise AND operator).
a(n) = A030101(n) - (n AND A030101(n)).
a(n) = A030101(n) - A175297(n) (for any n > 0).
a(n) = 0 iff n belongs to A006995.
EXAMPLE
The first terms, alongside the corresponding binary expansions, are:
n a(n) bin(n) bin(a(n)) bin(n OR a(n))
-- ---- ------ --------- --------------
0 0 0 0 0
1 0 1 0 1
2 1 10 1 11
3 0 11 0 11
4 1 100 1 101
5 0 101 0 101
6 1 110 1 111
7 0 111 0 111
8 1 1000 1 1001
9 0 1001 0 1001
10 5 1010 101 1111
11 4 1011 100 1111
12 3 1100 11 1111
13 2 1101 10 1111
14 1 1110 1 1111
15 0 1111 0 1111
MATHEMATICA
A370427[n_] := With[{r = IntegerReverse[n, 2]}, r - BitAnd[n, r]];
Array[A370427, 2^7, 0] (* Paolo Xausa, Feb 20 2024 *)
PROG
(PARI) a(n) = my (r = fromdigits(Vecrev(binary(n)), 2)); r - bitand(n, r)
CROSSREFS
Cf. A006995, A030101, A175297, A344220 (XOR variant).
Sequence in context: A073743 A021652 A360778 * A022961 A023447 A280916
KEYWORD
nonn,base,easy,look
AUTHOR
Rémy Sigrist, Feb 18 2024
STATUS
approved

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Last modified June 23 10:38 EDT 2024. Contains 373643 sequences. (Running on oeis4.)