A227921 Odd odious numbers (A000069), all divisors of which are odious.
1, 7, 11, 13, 19, 31, 37, 41, 47, 49, 59, 61, 67, 73, 79, 91, 97, 103, 107, 109, 121, 127, 131, 133, 137, 143, 151, 157, 167, 173, 179, 181, 191, 193, 199, 211, 217, 223, 227, 229, 233, 239, 241, 247, 251, 259, 271, 283, 307, 313, 331, 341, 361, 367, 379, 397, 403
Offset: 1
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
-
Maple
odious:= proc(n) option remember; n::odd xor procname(floor(n/2)) end proc: odious(0):= false: odious(1):= true: filter:= proc(n) andmap(odious, numtheory:-divisors(n)) end proc: select(filter, [seq(i,i=1..500,2)]); # Robert Israel, Aug 18 2019
-
Mathematica
odiusQ[n_]:=OddQ[Total[IntegerDigits[n,2]]]; Select[Range[1,411,2], odiusQ[ #]&&AllTrue[Divisors[#],odiusQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jun 08 2019 *)
-
PARI
isodious(n) = {b = binary(n); sum(i=1, #b, b[i]==1) % 2;} isok(n) = {if (!(n % 2), return (0)); fordiv(n, div, if (! isodious(div), return (0))); return (1);} \\ Michel Marcus, Oct 12 2013
Comments