OFFSET
1,1
EXAMPLE
a(1)=2 (2nd composite/3 = 6/3 = 2, which is prime).
a(2)=4 (4th composite/3 = 9/3 = 3, which is prime).
MATHEMATICA
Position[Select[Range[1000], CompositeQ], _?(PrimeQ[#/3]&)]//Flatten (* Harvey P. Dale, Aug 06 2022 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Juri-Stepan Gerasimov, Jul 29 2009
EXTENSIONS
48 replaced by 49, 62 replaced by 63, 96 by 97, etc. - R. J. Mathar, Oct 09 2009
STATUS
approved