|
| |
|
|
A095283
|
|
Primes whose binary-expansion ends with an odd number of 1's.
|
|
4
|
|
|
|
5, 7, 13, 17, 23, 29, 31, 37, 41, 53, 61, 71, 73, 89, 97, 101, 103, 109, 113, 127, 137, 149, 151, 157, 167, 173, 181, 193, 197, 199, 223, 229, 233, 241, 257, 263, 269, 277, 281, 293, 311, 313, 317, 337, 349, 353, 359, 373, 383, 389, 397, 401, 409
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
|
|
|
MAPLE
|
q:= proc(n) local i, l, r; l, r:= convert(n, base, 2), 0;
for i to nops(l) while l[i]=1 do r:=r+1 od; is(r, odd)
end:
|
|
|
MATHEMATICA
|
Select[Prime[Range[100]], MatchQ[IntegerDigits[#, 2], {b:(1)..}|{___, 0, b:(1)..} /; OddQ[Length[{b}]]]&] (* Jean-François Alcover, Jan 03 2022 *)
|
|
|
PROG
|
(Python)
from sympy import isprime
def ok(n): b = bin(n); return (len(b)-len(b.rstrip("1")))%2 and isprime(n)
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn,base,easy
|
|
|
AUTHOR
|
|
|
|
STATUS
|
approved
|
| |
|
|
