A100456 Values of n for which the decimal number 10...050...01 is an n-digit prime.

3, 5, 9, 11, 17, 55, 331, 461, 475, 739, 971, 1257, 1751, 1929, 2839, 8167

Offset: 1

Author

Harvey Dubner (harvey(AT)dubner.com), Nov 23 2004

Keywords

• nonn
• base
• more

Comments

a(17) > 53125. - Robert Price, Apr 14 2013

Three is a term because 151 is a prime, thus illustrating that zeros are optional in the resulting primes. - Harvey P. Dale, Oct 08 2019

Crossrefs

Cf. A100028.

Programs

Mathematica

IntegerLength/@Select[Table[FromDigits[Join[PadRight[{1},n,0],{5},PadLeft[ {1},n,0]]],{n,5000}],PrimeQ] (* Harvey P. Dale, Oct 08 2019 *)

Extensions

Corrected by T. D. Noe, Oct 25 2006