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A274904
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Largest prime factor of 6^n + 1.
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6
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2, 7, 37, 31, 1297, 101, 97, 197, 98801, 46441, 6781, 51828151, 1678321, 37571, 5030761, 1950271, 4709377, 12690943, 55117, 48713705333, 68754507401, 2527867231, 863017, 990000731, 473896897, 3655688315536801, 6291946695217, 883383463, 81035189089
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OFFSET
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0,1
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LINKS
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J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
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FORMULA
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EXAMPLE
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6^3 + 1 = 217 = 7*31, so a(3) = 31.
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MATHEMATICA
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Table[FactorInteger[6^n + 1][[-1, 1]], {n, 0, 40}]
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PROG
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(Magma) [Maximum(PrimeDivisors(6^n+1)): n in [0..40]];
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CROSSREFS
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Cf. similar sequences listed in A274903.
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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a(409)-a(420) in b-file from Max Alekseyev, Apr 25 2022, Aug 26 2023
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STATUS
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approved
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