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 A051130 Indices of prime Bell numbers A000110. 4
 2, 3, 7, 13, 42, 55, 2841 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Bell(2841) has been certified to be a prime using Primo. This took 17 months on a P3-800, a P4-2400 and finally a P4-2800. There are no other terms below 6000. - Ignacio Larrosa Cañestro, Feb 13 2004 LINKS E. T. Bell, Exponential numbers, Amer. Math. Monthly, 41 (1934), 411-419. Eric Weisstein's World of Mathematics, Bell Number Eric Weisstein's World of Mathematics, Integer Sequence Primes EXAMPLE The Bell numbers Bell(2)=2, Bell(3)=5, Bell(7)=877 etc. are primes. MATHEMATICA Reap[For[n = 1, n <= 3000, n++, If[PrimeQ[BellB[n]], Print[n]; Sow[n]]]][[2, 1]] (* Jean-François Alcover, Jun 05 2012 *) Select[Range[2900], PrimeQ[BellB[#]]&] (* Harvey P. Dale, Nov 08 2012 *) PROG (MAGMA) [n: n in [0..1000]|IsPrime(Bell(n))]; // Vincenzo Librandi, Jan 30 2016 CROSSREFS Cf. A000110, A051131. Sequence in context: A196419 A056893 * A078749 A046062 A096263 A007996 Adjacent sequences:  A051127 A051128 A051129 * A051131 A051132 A051133 KEYWORD hard,nonn,nice AUTHOR STATUS approved

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Last modified December 10 20:55 EST 2018. Contains 318049 sequences. (Running on oeis4.)