OFFSET
1,3
COMMENTS
a(n) is one fourth of the row product of the irregular triangle A281854.
MATHEMATICA
EulerPhi@ Select[Range[2, 130], ! IntegerQ@ PrimitiveRoot@ # &]/4 (* Michael De Vlieger, Feb 02 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Wolfdieter Lang, Feb 02 2017
STATUS
approved