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 A202424 Primes of the form n!*n!! - 1. 1
 3, 17, 191, 13934591999, 414935135999, 841488455807999, 12256784251917004799999, 91886617089132974573617151999999, 20572604964026488636856632501862399999999, 624332713268595066448813603451600045741761894966886399999999999 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS For n > 4, the last digits of the prime numbers are of the form 999, 999, 99999, 999999,...,...99999. LINKS EXAMPLE 191 is in the sequence because, for n = 4, 4!*4!! - 1 = 24*8 - 1 = 191. MATHEMATICA a={}; Do[p=n!*n!!-1; If[PrimeQ[p], AppendTo[a, p]], {n, 10^3}]; Print[a]; PROG (MAGMA) a:=func< n | Factorial(n)*(&*[n..2 by -2])-1 >; [ a(n): n in [0..78] | IsPrime(a(n)) ];  // Bruno Berselli, Dec 19 2011 CROSSREFS Cf. A000142, A006882, A202426. Sequence in context: A088678 A195067 A158885 * A335343 A133991 A210898 Adjacent sequences:  A202421 A202422 A202423 * A202425 A202426 A202427 KEYWORD nonn AUTHOR Michel Lagneau, Dec 19 2011 STATUS approved

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Last modified May 27 12:58 EDT 2022. Contains 354097 sequences. (Running on oeis4.)