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A161601
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Positive integers k that are less than the value of the reversal of k's representation in binary.
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6
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11, 19, 23, 35, 37, 39, 43, 47, 55, 67, 69, 71, 75, 77, 79, 83, 87, 91, 95, 103, 111, 131, 133, 135, 137, 139, 141, 143, 147, 149, 151, 155, 157, 159, 163, 167, 171, 173, 175, 179, 183, 187, 191, 199, 203, 207, 215, 223, 239, 259, 261, 263, 265, 267, 269, 271
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OFFSET
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1,1
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COMMENTS
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By "reversal" of k's representation in binary, it is meant: write k in binary, reverse the order of its digits, and read the result as a binary value.
This sequence contains only odd integers.
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LINKS
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EXAMPLE
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37 = 100101_2; its digital reversal is 101001_2 = 41. Since 37 < 41, 37 is in this sequence.
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MAPLE
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a := proc (n) local n2, sz, rv: n2 := convert(n, base, 2): sz := nops(n2): rv := add(n2[j]*2^(sz-j), j = 1 .. sz): if n < rv then n else end if end proc; seq(a(n), n = 1 .. 280); # Emeric Deutsch, Jun 28 2009
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MATHEMATICA
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Select[Range[300], FromDigits[Reverse[IntegerDigits[#, 2]], 2]>#&] (* Harvey P. Dale, Mar 19 2016 *)
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PROG
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(Python)
from itertools import count, islice
def A161601_gen(startvalue=1): # generator of terms >= startvalue
return filter(lambda n:n<int(bin(n)[-1:1:-1], 2), count(max(startvalue|1, 1), 2))
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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