A100028 Values of n for which the decimal number 10...030...01 is an n-digit prime.

3, 5, 7, 9, 23, 29, 33, 185, 267, 307, 757, 897, 1571, 2977, 3831, 4595, 6573, 9511, 11651, 15641, 68885, 69883

Offset

1,1

Links

Table of n, a(n) for n=1..22.

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

Cf. A100026, A100027, A100456, A100457, A100458, A100459.

Sequence in context: A099995 A356177 A329364 * A053681 A135773 A357677

Adjacent sequences: A100025 A100026 A100027 * A100029 A100030 A100031

Keyword

nonn,base,more

Author

Harvey Dubner (harvey(AT)dubner.com), Nov 20 2004

Status

approved