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A100456
Values of n for which the decimal number 10...050...01 is an n-digit prime.
2
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
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
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