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A067887
Composite numbers k such that phi(k+1) < phi(k).
1
9, 21, 25, 27, 33, 35, 39, 45, 49, 51, 55, 57, 63, 65, 69, 75, 77, 81, 85, 87, 91, 93, 95, 99, 111, 115, 117, 119, 121, 123, 125, 129, 133, 135, 141, 143, 145, 147, 153, 155, 159, 161, 169, 171, 175, 177, 183, 185, 187, 189, 195, 201, 203, 205, 207, 209, 213
OFFSET
1,1
LINKS
MATHEMATICA
Select[Range[200], CompositeQ[#] && EulerPhi[# + 1] < EulerPhi[#] &] (* Amiram Eldar, Apr 29 2022 *)
CROSSREFS
Cf. A000010.
Sequence in context: A317789 A333039 A266000 * A345330 A174870 A141603
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Mar 02 2002
STATUS
approved