OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..10000
EXAMPLE
1*10 - (-1)^1 = 11 is prime, so 1 is a term;
2*10 - (-1)^2 = 19 is prime, so 2 is a term;
3*10 - (-1)^3 = 31 is prime, so 3 is a term;
4*10 - (-1)^4 = 39 = 3*13, so 4 is not a term.
MATHEMATICA
Select[If[PrimeQ[10*# - (-1)^#], #] & /@ Range[6!], IntegerQ] (* G. C. Greubel, May 15 2016 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Juri-Stepan Gerasimov, Oct 14 2009
EXTENSIONS
Corrected (77 removed) by R. J. Mathar, May 21 2010
STATUS
approved