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 A100028 Values of n for which the decimal number 10...030...01 is an n-digit prime. 7
 3, 5, 7, 9, 23, 29, 33, 185, 267, 307, 757, 897, 1571, 2977, 3831, 4595, 6573, 9511, 11651, 15641, 68885, 69883 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS 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: A241175 A099995 A329364 * A053681 A135773 A262029 Adjacent sequences:  A100025 A100026 A100027 * A100029 A100030 A100031 KEYWORD nonn,base AUTHOR Harvey Dubner (harvey(AT)dubner.com), Nov 20 2004 STATUS approved

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Last modified October 31 05:06 EDT 2020. Contains 338098 sequences. (Running on oeis4.)