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A140538
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Greatest prime factor of 2*n^4 + 1.
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2
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3, 11, 163, 19, 139, 2593, 1601, 2731, 1193, 113, 227, 619, 577, 8537, 73, 43691, 55681, 209953, 307, 9697, 388963, 52057, 1091, 337, 260417, 304651, 3011, 4937, 471521, 1620001, 691, 5419, 32491, 46889, 90947, 25643, 11057, 15619, 7499, 7793
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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a(2)= 11 because 2*2^4+1 = 33 = 3*11, greatest prime factor is 11.
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MATHEMATICA
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Table[Max[Transpose[FactorInteger[2 n^4 + 1]][[1]]], {n, 50}] (* Vincenzo Librandi, Feb 17 2015 *)
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PROG
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(PARI) a(n) = f = factor(2*n^4+1); f[#f~, 1]; \\ Michel Marcus, Aug 28 2013
(Magma) [#f eq 0 select 1 else f[ #f][1] where f is Factorization(2*n^4 + 1): n in [1..50]]; // Vincenzo Librandi, Feb 17 2015
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CROSSREFS
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KEYWORD
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easy,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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