

A231271


Numbers n such that n and n+d are both odious (A000069) or both evil (A001969) for every divisor d of n.


3



1, 5, 7, 9, 13, 17, 23, 29, 31, 37, 41, 49, 53, 61, 71, 73, 85, 89, 97, 101, 103, 109, 113, 119, 125, 127, 129, 133, 137, 149, 151, 157, 167, 173, 181, 193, 197, 199, 217, 223, 229, 233, 241, 249, 257, 263, 269, 277, 281, 293, 311, 313, 317, 321, 325, 337, 341
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OFFSET

1,2


COMMENTS

A prime p is a term iff its binary expansion ends in odd number of 1's (A095283). All terms are in A079523.


LINKS

Peter J. C. Moses, Table of n, a(n) for n = 1..10000


EXAMPLE

Odious number n=341 has divisors {1,11,31,341}. Since numbers 341+1=342, 341+11=352, 341+31=372, 341+341=682 all are odious, then 341 is in the sequence.


MATHEMATICA

odiousQ[n_] := OddQ[DigitCount[n, 2][[1]]]; selQ[n_] := Length[Union[Map[odiousQ, Flatten[{n, Map[n+#&, Divisors[n]]}]]]] == 1; Select[Range[200], selQ] (* Peter J. C. Moses, Nov 08 2013 *)


CROSSREFS

Cf. A000069, A001969, A079523, A095283.
Sequence in context: A111083 A050550 A079523 * A039504 A097280 A155732
Adjacent sequences: A231268 A231269 A231270 * A231272 A231273 A231274


KEYWORD

nonn,base


AUTHOR

Vladimir Shevelev, Nov 06 2013


EXTENSIONS

More terms from Peter J. C. Moses, Nov 08 2013


STATUS

approved



