|
|
A209211
|
|
Numbers n such that n-1 and phi(n) are relatively prime.
|
|
10
|
|
|
1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 54, 56, 58, 60, 62, 64, 68, 72, 74, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 114, 116, 118, 120, 122, 126, 128, 132, 134, 136, 138
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
|
|
LINKS
|
|
|
MAPLE
|
select(n -> igcd(n-1, numtheory:-phi(n)) = 1, [$1..1000]); # Robert Israel, Nov 09 2015
|
|
MATHEMATICA
|
Select[Range[200], GCD[# - 1, EulerPhi[#]] == 1 &]
|
|
PROG
|
(Haskell)
a209211 n = a209211_list !! (n-1)
a209211_list = filter (\x -> (x - 1) `gcd` a000010 x == 1) [1..]
(PARI) isok(n) = gcd(n-1, eulerphi(n)) == 1; \\ Michel Marcus, Sep 26 2016
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|