OFFSET
1,1
FORMULA
a(n) = 2*(A171376(n+1))+1. - Chai Wah Wu, Aug 20 2015
EXAMPLE
The corresponding primes are 131, 10301, 1003001, 100030001, 10000000000300000000001, etc.
MATHEMATICA
IntegerLength/@Select[Table[FromDigits[Join[PadRight[{1}, n, 0], {3}, PadLeft[ {1}, n, 0]]], {n, 35000}], PrimeQ] (* Harvey P. Dale, Dec 20 2019 *)
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Harvey Dubner (harvey(AT)dubner.com), Nov 20 2004
STATUS
approved