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A327187
For any n >= 0: consider the different ways to split the binary representation of n into two (possibly empty) parts, say with value x and y; a(n) is the least possible value of x XOR y (where XOR denotes the bitwise XOR operator).
3
0, 1, 1, 0, 1, 0, 3, 2, 1, 0, 0, 1, 3, 2, 1, 0, 1, 0, 0, 1, 5, 4, 4, 5, 3, 2, 1, 0, 7, 6, 5, 4, 1, 0, 0, 1, 0, 1, 2, 3, 5, 4, 7, 6, 1, 0, 3, 2, 3, 2, 1, 0, 2, 3, 0, 1, 7, 6, 5, 4, 3, 2, 1, 0, 1, 0, 0, 1, 0, 1, 2, 3, 9, 8, 8, 9, 8, 9, 10, 11, 5, 4, 7, 6, 1, 0
OFFSET
0,7
LINKS
FORMULA
a(n) = 0 iff n = 0 or n belongs to A175468.
EXAMPLE
For n=42:
- the binary representation of 42 is "101010",
- there are 7 ways to split it:
- "" and "101010": x=0 and y=42: 0 XOR 42 = 42,
- "1" and "01010": x=1 and y=10: 1 XOR 10 = 11,
- "10" and "1010": x=2 and y=10: 2 XOR 10 = 8,
- "101" and "010": x=5 and y=2: 5 XOR 2 = 7,
- "1010" and "10": x=10 and y=2: 10 XOR 2 = 8,
- "10101" and "0": x=21 and y=0: 21 XOR 0 = 21,
- "101010" and "": x=42 and y=0: 42 XOR 0 = 42,
- hence a(42) = 7.
PROG
(PARI) a(n) = my (v=oo, b=binary(n)); for (w=0, #b, v=min(v, bitxor(fromdigits(b[1..w], 2), fromdigits(b[w+1..#b], 2)))); v
CROSSREFS
See A327186 for other variants.
Cf. A175468.
Sequence in context: A058257 A330959 A083199 * A274537 A305234 A021761
KEYWORD
nonn,look,base
AUTHOR
Rémy Sigrist, Aug 25 2019
STATUS
approved