A067887 Composite numbers k such that phi(k+1) < phi(k).

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

Amiram Eldar, Table of n, a(n) for n = 1..10000

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

Adjacent sequences: A067884 A067885 A067886 * A067888 A067889 A067890

Keyword

easy,nonn

Author

Benoit Cloitre, Mar 02 2002

Status

approved