OFFSET
1,2
EXAMPLE
4=(3+5)/2, so 4 does not belong.
MATHEMATICA
With[{nn=400}, Select[Complement[Range[nn], Union[Flatten[ Table[ Select[Mean/@Partition[ Prime[Range[PrimePi[nn]]], n, 1], IntegerQ], {n, 2, PrimePi[nn]}]]]], #<nn/2&]] (* Harvey P. Dale, Apr 08 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Giovanni Resta, Feb 10 2006
STATUS
approved