OFFSET
1,1
EXAMPLE
If i=1, then
c(c(1)-3)-3=c(4-3)-3=4-3=1 (nonprime).
If i=2, then
c(c(2)-3)-3=c(6-3)-3=c(3)-3=8-3=5=a(1).
If i=3, then
c(c(3)-3)-3=c(8-3)-3=c(5)-3=10-3=7=a(2).
If i=4, then
c(c(4)-3)-3=c(9-3)-3=c(6)-3=12-3=9 (nonprime).
If i=5, then
c(c(5)-3)-3=c(10-3)-3=c(7)-3=14-3=11=a(3),
etc.
MATHEMATICA
Module[{nn=500, cmps}, cmps=Select[Range[nn], CompositeQ]; Select[ Table[ cmps[[cmps[[n]]-3]]-3, {n, 250}], PrimeQ]] (* Harvey P. Dale, Jun 17 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Sep 03 2008
EXTENSIONS
43, 59, 73, 227, 229, 347, 367 inserted by R. J. Mathar, Sep 05 2008
STATUS
approved