OFFSET
1,1
EXAMPLE
1^2+3*1+1 = 5 prime so a(1) = 5.
2^2+3*2+1 = 11 prime so a(2) = 11.
6^2+3*6+1 = 55 = 5*11 composite so a(6) = 0.
MATHEMATICA
Table[t=n^2+3n+1; If[PrimeQ[t], t, 0], {n, 50}] (* James C. McMahon, Feb 21 2024 *)
CROSSREFS
KEYWORD
nonn,less
AUTHOR
Pierre CAMI, Jun 06 2005
STATUS
approved