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A258433
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Primes with repdigit indices (in decimal).
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2
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2, 3, 5, 7, 11, 13, 17, 19, 23, 31, 79, 137, 193, 257, 317, 389, 457, 523, 607, 1399, 2239, 3119, 4019, 4973, 5903, 6907, 7907, 8933, 19583, 30911, 42473, 54581, 66889, 79357, 92003, 104723, 117763, 252233, 393191, 538259, 686671, 836833, 989999, 1144153, 1299689, 1456667, 3080969, 4767181, 6495109, 8251153
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OFFSET
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1,1
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COMMENTS
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Elements of this sequence are the first 9 primes, then the 11th, 22nd, 33rd, ... , 99th, 111th, 222nd, etc. This is a somewhat remarkable sequence because of certain digital coincidences (see Prime Curios links).
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LINKS
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FORMULA
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EXAMPLE
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The first prime skipped is the 10th, 29, so that a(10)=31. Then follows a(11)=79, a(12)=137, a(13)=193, etc.: The 22nd, 33rd, and 44th primes, and so on.
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MATHEMATICA
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Prime[#]&/@(FromDigits/@Flatten[Table[PadRight[{}, k, n], {k, 6}, {n, 9}], 1]) (* Harvey P. Dale, Mar 25 2019 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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