

A317407


The "OOPS" numbers  numbers with ones in all oddnumbered positions of the binary representation of n.


1



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

1,2


COMMENTS

Here we number positions starting with the most significant digit as position 1, and continue to the right down to the least significant digit.
From David A. Corneth, Jul 29 2018: (Start)
1 is in the sequence.
If k is in the sequence then so is 2k+1.
(End)
If A070939(k) is odd and k is in the sequence then so is 2*k.  Robert Israel, Jul 31 2018


LINKS

Robert Israel, Table of n, a(n) for n = 1..10000


EXAMPLE

23 is in the sequence because its binary representation is 10111, and it has ones in positions 1,3,5.


MAPLE

S[1]:= [1]:
for n from 2 to 10 do
if n::odd then S[n]:= map(t > 2*t+1, S[n1])
else S[n]:= map(t > (2*t, 2*t+1), S[n1])
fi
od;
map(op, [seq(S[i], i=1..10)]); # Robert Israel, Jul 31 2018


PROG

(PARI) isok(n) = {my(b=binary(n)); forstep (i=1, #b, 2, if (!b[i], return (0)); ); return (1); } \\ Michel Marcus, Jul 29 2018


CROSSREFS

Cf. A032911, A070939.
Sequence in context: A194948 A266679 A285257 * A191211 A263133 A254860
Adjacent sequences: A317404 A317405 A317406 * A317408 A317409 A317410


KEYWORD

nonn,base


AUTHOR

Jeffrey Shallit, Jul 28 2018


STATUS

approved



