




OFFSET

1,1


COMMENTS

Except for the first term, each term must both begin and end with a "1" because each term greater than 2 must end in a "1" and if a term begins with a "2" the sum of the digits of the term will be divisible by 3 and thus the term is not a prime.  Harvey P. Dale, Jun 22 2019
The next term (a(5)) has 139 digits and a(6) has 627 digits.  Harvey P. Dale, Jun 22 2019


LINKS

Table of n, a(n) for n=1..4.


MATHEMATICA

Join[{2}, Select[Table[FromDigits[PadRight[{}, 2n+1, {1, 2}]], {n, 30}], PrimeQ]] (* Harvey P. Dale, Jun 22 2019 *)


CROSSREFS

Cf. A028359.
Sequence in context: A051118 A324439 A218169 * A303433 A253264 A124368
Adjacent sequences: A168532 A168533 A168534 * A168536 A168537 A168538


KEYWORD

nonn


AUTHOR

Zak Seidov, Nov 28 2009


STATUS

approved



