|
|
A370597
|
|
Even numbers k such that gcd(k, A007814(k)) = 1.
|
|
1
|
|
|
2, 6, 8, 10, 14, 18, 22, 26, 30, 32, 34, 38, 40, 42, 46, 50, 54, 56, 58, 62, 66, 70, 74, 78, 82, 86, 88, 90, 94, 96, 98, 102, 104, 106, 110, 114, 118, 122, 126, 128, 130, 134, 136, 138, 142, 146, 150, 152, 154, 158, 162, 166, 170, 174, 178, 182, 184, 186, 190, 194, 198, 200
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
The asymptotic density of this sequence is Sum_{k>=0} (phi(2*k+1)/((2*k+1)*2^(2*k+2))) = 0.30845704942203403516..., where phi is Euler's totient function (A000010).
|
|
LINKS
|
|
|
MATHEMATICA
|
Select[2 * Range[200], CoprimeQ[#, IntegerExponent[#, 2]] &]
|
|
PROG
|
(PARI) is(n) = !(n%2) && gcd(n, valuation(n, 2)) == 1;
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|