Search: id:A006990
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%I A006990 M1541
%S A006990 2,5,23,113,719,5039,40289,362867,3628789,39916787,479001599,
%T A006990 6227020777,87178291199,1307674367953,20922789887947,355687428095941,
%U A006990 6402373705727959,121645100408831899,2432902008176639969
%N A006990 Largest prime <= n!.
%C A006990 Conjecture: for n > 2, n! - a(n) is 1 or a prime i.e. a non-composite 
               number. E.g. 3! - 5 = 1, 5!- 113 = 7 etc. - Amarnath Murthy (amarnath_murthy(AT)yahoo.com), 
               Mar 19 2002
%D A006990 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%t A006990 PrevPrime[ n_Integer ] := Module[ {k = n - 1}, While[ ! PrimeQ[ k ], 
               k-- ]; k ]; Table[ PrevPrime[ n! ], {n, 3, 25} ]
%Y A006990 Sequence in context: A100299 A038833 A003501 this_sequence A032182 A165902 
               A167142
%Y A006990 Adjacent sequences: A006987 A006988 A006989 this_sequence A006991 A006992 
               A006993
%K A006990 nonn
%O A006990 2,1
%A A006990 N. J. A. Sloane (njas(AT)research.att.com), Robert G. Wilson v (rgwv(AT)rgwv.com)
%E A006990 More terms from Jud McCranie (j.mccranie(AT)comcast.net); also from Robert 
               G. Wilson v (rgwv(AT)rgwv.com), Jan 03 2001

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