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 A163078 Numbers k such that k\$ - 1 is prime. Here '\$' denotes the swinging factorial function (A056040). 3
 3, 4, 5, 6, 7, 10, 13, 15, 18, 30, 35, 39, 41, 47, 49, 58, 83, 86, 102, 111, 137, 151, 195, 205, 226, 229, 317, 319, 321, 368, 389, 426, 444, 477, 534, 558, 567, 738, 804, 882, 1063, 1173, 1199, 1206, 1315, 1624, 1678, 1804, 2371, 2507, 2541, 2844, 3084, 3291 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..54. Peter Luschny, Die schwingende Fakultät und Orbitalsysteme, August 2011. Peter Luschny, Swinging Primes. EXAMPLE 4\$ - 1 = 6 - 1 = 5 is prime, so 4 is in the sequence. MAPLE a := proc(n) select(x -> isprime(A056040(x)-1), [\$0..n]) end: MATHEMATICA fQ[n_] := PrimeQ[ -1 + 2^(n - Mod[n, 2])*Product[k^((-1)^(k + 1)), {k, n}]]; Select[ Range@ 3647, fQ] (* Robert G. Wilson v, Aug 09 2010 *) PROG (PARI) is(k) = ispseudoprime(k!/(k\2)!^2-1); \\ Jinyuan Wang, Mar 22 2020 CROSSREFS Cf. A002982, A056040, A163077, A163079, A163080. Sequence in context: A271376 A087190 A085038 * A050034 A039056 A326754 Adjacent sequences: A163075 A163076 A163077 * A163079 A163080 A163081 KEYWORD nonn AUTHOR Peter Luschny, Jul 21 2009 EXTENSIONS a(42)-a(54) from Robert G. Wilson v, Aug 09 2010 STATUS approved

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Last modified March 1 22:23 EST 2024. Contains 370443 sequences. (Running on oeis4.)