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 A006990 Largest prime <= n!. (Formerly M1541) 17
 2, 5, 23, 113, 719, 5039, 40289, 362867, 3628789, 39916787, 479001599, 6227020777, 87178291199, 1307674367953, 20922789887947, 355687428095941, 6402373705727959, 121645100408831899, 2432902008176639969, 51090942171709439969, 1124000727777607679927 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS Conjecture: For n >= 2, n! - a(n) is 1 or a prime, see A033933. - Amarnath Murthy, Mar 19 2002 a(n) is the largest prime divisor of (n!)! of the sequence A000197. - Stanislav Sykora, Jul 14 2014 REFERENCES N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Donovan Johnson, Table of n, a(n) for n = 2..400 R. G. Wilson v, Letter to N. J. A. Sloane, Oct. 1993 MATHEMATICA PrevPrime[ n_Integer ] := Module[ {k = n - 1}, While[ ! PrimeQ[ k ], k-- ]; k ]; Table[ PrevPrime[ n! ], {n, 3, 25} ] Join[{2}, NextPrime[Range[3, 30]!, -1]] (* Harvey P. Dale, Jan 24 2014 *) CROSSREFS Cf. A000142, A007917. Sequence in context: A279819 A249606 A003501 * A242227 A032182 A165902 Adjacent sequences:  A006987 A006988 A006989 * A006991 A006992 A006993 KEYWORD nonn AUTHOR EXTENSIONS More terms from Jud McCranie; also from Robert G. Wilson v, Jan 03 2001 STATUS approved

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Last modified January 18 16:27 EST 2020. Contains 331011 sequences. (Running on oeis4.)