OFFSET
1,1
COMMENTS
a(13) has 1436 decimal digits. - Vincenzo Librandi, Jul 19 2012
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..12
MATHEMATICA
a = Delete[Union[Table[If[PrimeQ[Sum[7^i, {i, 0, n}] + 1 - Mod[Sum[7^i, {i, 0, n}], 2]] == True, Sum[7^i, {i, 0, n}] + 1 - Mod[Sum[7^i, {i, 0, n}], 2], 0], {n, 0, 200}]], 1]
CROSSREFS
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Mar 15 2005
EXTENSIONS
Corrected a(8). - Vincenzo Librandi, Jul 19 2012
STATUS
approved