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A341798
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a(n) is the starting position of the first occurrence of the binary reversal of n in the binary Champernowne word (A030190).
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1
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0, 1, 0, 1, 7, 2, 0, 4, 19, 6, 8, 1, 23, 2, 3, 15, 51, 18, 21, 5, 7, 26, 0, 11, 56, 22, 8, 1, 66, 2, 14, 46, 131, 50, 54, 17, 20, 63, 58, 4, 143, 6, 27, 25, 23, 77, 10, 41, 137, 55, 21, 34, 7, 28, 0, 11, 149, 65, 8, 1, 173, 13, 45, 125, 323, 130, 135, 49, 53
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listen;
history;
text;
internal format)
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OFFSET
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0,5
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COMMENTS
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This sequence is a variant of A030304.
When considering the binary reversal of a positive number, the trailing zeros in that number turn into leading zeros in its binary reversal; we keep those leading zeros.
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LINKS
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FORMULA
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EXAMPLE
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For n = 4:
- the binary reversal of 4 is "001",
- the binary Champernowne word begins "0110111001011...",
- the first occurrence of "001" in this word starts at position 7,
- so a(4) = 7.
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PROG
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(Perl) See Links section.
(Python)
from itertools import count, islice
def agen():
k, chap = 0, "0"
for n in count(0):
target = bin(n)[2:][::-1]
while chap.find(target) == -1: k += 1; chap += bin(k)[2:]
yield chap.find(target)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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