

A051130


Indices of prime Bell numbers A000110.


3




OFFSET

1,1


COMMENTS

Bell(2841) has been certified to be a prime using Primo. This took 17 months on a P3800, a P42400 and finally a P42800. There are no other terms below 6000.  Ignacio Larrosa Cañestro, Feb 13 2004


REFERENCES

E. T. Bell, Exponential numbers, Amer. Math. Monthly, 41 (1934), 411419.


LINKS

Table of n, a(n) for n=1..7.
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]] (* JeanFrançois Alcover, Jun 05 2012 *)
Select[Range[2900], PrimeQ[BellB[#]]&] (* Harvey P. Dale, Nov 08 2012 *)


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

Ignacio Larrosa Cañestro


STATUS

approved



