OFFSET
1,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
a(1)=1 because 3*prime(1)-4=2 is prime and 3*prime(1)+4=10 is composite; a(2)=4 because 3*prime(4)-4=17 is prime and 3*prime(4)+4=25 is composite.
MATHEMATICA
Select[Range[200], Total[Boole[PrimeQ[3Prime[#]+{4, -4}]]]==1&] (* Harvey P. Dale, May 08 2019 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Juri-Stepan Gerasimov, Mar 14 2010
EXTENSIONS
Corrected by Charles R Greathouse IV, Mar 19 2010
STATUS
approved