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A122072
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Greatest prime less than 10n.
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7
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7, 19, 29, 37, 47, 59, 67, 79, 89, 97, 109, 113, 127, 139, 149, 157, 167, 179, 181, 199, 199, 211, 229, 239, 241, 257, 269, 277, 283, 293, 307, 317, 317, 337, 349, 359, 367, 379, 389, 397, 409, 419, 421, 439, 449, 457, 467, 479, 487, 499, 509, 509, 523, 523
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OFFSET
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1,1
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COMMENTS
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First repeating terms are 199, 317, 509, 523, 619, 839, 887, 1069, 1129, 1129, 1259, 1327, 1327, 1327, 1409, 1459, 1499, 1637, 1669, 1669, 1709, 1759, 1789, 1847, 1889, 1913, 1951.
a(n) is also the greatest prime factor among composites (A002808) below 20n. For primes of the form 20n + 1, see A141881. - Lekraj Beedassy, Jan 23 2012
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LINKS
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MATHEMATICA
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Table[Prime[PrimePi[10 n]], {n, 54}] (* Jayanta Basu, May 24 2013 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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