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 A163080 Primes p such that p\$ - 1 is also prime. Here '\$' denotes the swinging factorial function (A056040). 3
 3, 5, 7, 13, 41, 47, 83, 137, 151, 229, 317, 389, 1063 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n) are the primes in A163078. REFERENCES Peter Luschny, "Divide, swing and conquer the factorial and the lcm{1,2,...,n}", preprint, April 2008. LINKS Peter Luschny, Swinging Primes. EXAMPLE 3 is prime and 3\$ - 1 = 5 is prime, so 3 is in the sequence. MAPLE a := proc(n) select(isprime, select(k -> isprime(A056040(k)-1), [\$0..n])) end: MATHEMATICA sf[n_] := n!/Quotient[n, 2]!^2; Select[Prime /@ Range[200], PrimeQ[sf[#] - 1] &] (* Jean-François Alcover, Jun 28 2013 *) CROSSREFS Cf. A163079, A163078, A103317. Sequence in context: A075557 A244452 A057187 * A141414 A236464 A064268 Adjacent sequences:  A163077 A163078 A163079 * A163081 A163082 A163083 KEYWORD nonn AUTHOR Peter Luschny, Jul 21 2009 STATUS approved

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Last modified December 13 17:35 EST 2018. Contains 318086 sequences. (Running on oeis4.)