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A081641
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a(n) = n-th prime of class 13- according to the Erdős-Selfridge classification.
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4
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36449279, 53065907, 59681213, 69096887, 132756479, 135388367, 164255999, 179043637, 188991053, 207290663, 241560239, 279709259, 309550999, 364492781, 372993983, 377982103, 398007431, 406165099, 425633717, 445901987, 447609067, 516737983
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OFFSET
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1,1
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REFERENCES
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R. K. Guy, Unsolved Problems in Number Theory, A18.
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LINKS
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MATHEMATICA
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PrimeFactors[n_Integer] := Flatten[ Table[ #[[1]], {1}] & /@ FactorInteger[n]]; f[n_Integer] := Block[{m = n}, If[m == 0, m = 1, While[ IntegerQ[m/2], m /= 2]; While[ IntegerQ[m/3], m /= 3]]; Apply[Times, PrimeFactors[m] - 1]]; ClassMinusNbr[n_] := Length[ NestWhileList[f, n, UnsameQ, All]] - 3; Prime[ Select[ Range[23733333], ClassMinusNbr[ Prime[ # ]] == 12 &]]
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PROG
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CROSSREFS
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Cf. A005113, A005105, A005106, A005107, A005108, A081633, A081633, A081635, A081636, A081637, A081638.
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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