|
|
A366641
|
|
Squarefree numbers that are coprime to the terms of A366640.
|
|
2
|
|
|
1, 2, 3, 6, 7, 11, 13, 14, 17, 19, 21, 22, 23, 26, 29, 31, 33, 34, 37, 38, 39, 41, 42, 43, 46, 47, 51, 53, 57, 58, 59, 61, 62, 66, 67, 69, 71, 73, 74, 77, 78, 82, 83, 86, 87, 89, 91, 93, 94, 97, 101, 102, 103, 106, 107, 109, 111, 113, 114, 118, 119, 122, 123, 127
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
First differs from A274546 at n = 42.
The asymptotic density of this sequence is 1/2.
|
|
LINKS
|
|
|
FORMULA
|
a(n) ~ 2*n.
Sum_{n>=1} 1/a(n)^s = (zeta(s)/zeta(2*s)) / Product_{p in A366640} (1 + 1/p^s), s>1.
|
|
MATHEMATICA
|
seq[max_] := With[{ps = {5, 79, 1831}}, If[max <= Max[ps], Select[Range[max], And @@ CoprimeQ[#, ps] && SquareFreeQ[#] &], Print["Add to ps more terms from A366640"]]]; seq[130]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|