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 A139467 Largest prime factor of n! + 2n - 1. 3
 2, 5, 11, 31, 43, 43, 163, 2689, 362897, 3628819, 179, 1908373, 800903, 101341, 13999747, 104099179, 10778406912001, 1300448327, 356961701, 62382102773760001, 10367823077693, 11437176299, 102338720137 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Florian Luca and Igor E. Shparlinski, On the largest prime factor of n! + 2^n - 1, Journal de Theorie des Nombres de Bordeaux 17 (2005), 859-870. MATHEMATICA a = {}; Do[k = n! + 2 n - 1; c = First[Last[FactorInteger[k]]]; AppendTo[a, c], {n, 1, 40}]; a (*Artur Jasinski*) Table[FactorInteger[n!+2n-1][[-1, 1]], {n, 30}] (* From Harvey P. Dale, Aug 31 2011 *) PROG (PARI) a(n)=my(f=factor(n!+2*n-1)[, 1]); f[#f] \\ Charles R Greathouse IV, Feb 01 2013 CROSSREFS Cf. A127986, A127987, A139023, A139024, A139464, A139465, A139466. Sequence in context: A131347 A079225 A139466 * A124481 A002862 A190865 Adjacent sequences:  A139464 A139465 A139466 * A139468 A139469 A139470 KEYWORD nonn AUTHOR Artur Jasinski, Apr 22 2008 STATUS approved

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