OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
a(1)=3 because prime(3-1)=3 and prime(3+1)=7 are not of the form 6k-1.
MATHEMATICA
pnQ[n_]:=NoneTrue[{Prime[n-1], Prime[n+1]}, IntegerQ[(#+1)/6]&]; Select[ Range[ 2, 300], pnQ] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 04 2019 *)
CROSSREFS
KEYWORD
nonn,easy,less
AUTHOR
Juri-Stepan Gerasimov, Feb 11 2010
EXTENSIONS
1 removed, 113 inserted - R. J. Mathar, Mar 09 2010
STATUS
approved