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

1,1

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

Links

Table of n, a(n) for n=1..16.

Mathematica

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

Crossrefs

Cf. A100028.

Sequence in context: A123069 A356537 A270836 * A059819 A074986 A307435

Adjacent sequences: A100453 A100454 A100455 * A100457 A100458 A100459

Keyword

nonn,base,more

Author

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

Extensions

Corrected by T. D. Noe, Oct 25 2006

Status

approved