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A317407
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The "OOPS" numbers -- numbers with ones in all odd-numbered positions of the binary representation of n.
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1
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1, 2, 3, 5, 7, 10, 11, 14, 15, 21, 23, 29, 31, 42, 43, 46, 47, 58, 59, 62, 63, 85, 87, 93, 95, 117, 119, 125, 127, 170, 171, 174, 175, 186, 187, 190, 191, 234, 235, 238, 239, 250, 251, 254, 255, 341, 343, 349, 351, 373, 375, 381, 383, 469, 471, 477, 479, 501
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OFFSET
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1,2
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COMMENTS
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Here we number positions starting with the most significant digit as position 1, and continue to the right down to the least significant digit.
1 is in the sequence.
If k is in the sequence then so is 2k+1.
(End)
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LINKS
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EXAMPLE
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23 is in the sequence because its binary representation is 10111, and it has ones in positions 1,3,5.
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MAPLE
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S[1]:= [1]:
for n from 2 to 10 do
if n::odd then S[n]:= map(t -> 2*t+1, S[n-1])
else S[n]:= map(t -> (2*t, 2*t+1), S[n-1])
fi
od;
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PROG
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(PARI) isok(n) = {my(b=binary(n)); forstep (i=1, #b, 2, if (!b[i], return (0)); ); return (1); } \\ Michel Marcus, Jul 29 2018
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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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