OFFSET
1,1
COMMENTS
a(6) > 50000 (if it exists).
MATHEMATICA
ParallelTable[If[PrimeQ[23^(n+19) + 19^(n+17) + 17^(n+13) + 13^(n+11) + 11^(n+7) + 7^(n+5) + 5^(n+3) + 3^(n+2) - 1], n, Nothing], {n, 30000}]
CROSSREFS
KEYWORD
nonn,hard,more,less
AUTHOR
Mikk Heidemaa, May 31 2019
STATUS
approved