OFFSET
1,3
MATHEMATICA
Table[k = 0; While[!PrimeQ[(3^n + k)*3^n - 1], k++]; k, {n, 72}]
lk[n_]:=Module[{c=3^n, k=0}, While[!PrimeQ[(c+k)c-1], k++]; k]; Array[lk, 70] (* Harvey P. Dale, Aug 19 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Nov 24 2011
STATUS
approved