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A161601
Positive integers k that are less than the value of the reversal of k's representation in binary.
6
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
OFFSET
1,1
COMMENTS
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.
LINKS
EXAMPLE
37 = 100101_2; its digital reversal is 101001_2 = 41. Since 37 < 41, 37 is in this sequence.
MAPLE
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
MATHEMATICA
Select[Range[300], FromDigits[Reverse[IntegerDigits[#, 2]], 2]>#&] (* Harvey P. Dale, Mar 19 2016 *)
PROG
(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))
A161601_list = list(islice(A161601_gen(), 20)) # Chai Wah Wu, Jan 19 2023
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Leroy Quet, Jun 14 2009
EXTENSIONS
Extended by Emeric Deutsch, Jun 28 2009
Edited by Jon E. Schoenfield, Feb 24 2019
STATUS
approved