

A100028


Values of n for which the decimal number 10...030...01 is an ndigit prime.


7



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

1,1


LINKS



FORMULA



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



KEYWORD

nonn,base,more


AUTHOR

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


STATUS

approved



