This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A076185 Numbers n such that n!! + 2 is prime. 18
 0, 1, 3, 5, 7, 9, 21, 23, 27, 57, 75, 103, 169, 219, 245, 461, 695, 1169, 3597, 3637, 7495, 27743, 28799, 32501 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(25) > 50000. - Robert Price, Jan 18 2015 a(1)=0 since 0!!=1 and 1+2 = 3 is prime. - Robert Price, Jan 18 2015 LINKS C. K. Caldwell, The Prime Glossary, Multifactorial prime C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75 Ken Davis, Status of Search for Multifactorial Primes. Joe McLean, Interesting Sources of Probable Primes The OpenPFGW Project, Primality Tester MATHEMATICA lst={}; Do[If[PrimeQ[n!!+2], AppendTo[lst, n]], {n, 0, 13^3}]; lst (* Vladimir Joseph Stephan Orlovsky, Sep 08 2008 *) Select[Range[0, 33000], PrimeQ[#!!+2]&] (* Harvey P. Dale, Jul 28 2017 *) CROSSREFS Cf. A006882, A080778 and A076186, A076188, A076189, A076190, A076193, A076194, A076195, A076196, A076197 for other values of s in n!! + 2^s. Sequence in context: A003219 A030142 A179085 * A101813 A134719 A273519 Adjacent sequences:  A076182 A076183 A076184 * A076186 A076187 A076188 KEYWORD nonn,more AUTHOR Zak Seidov, Nov 02 2002 EXTENSIONS Edited and extended (n<4096) by Hugo Pfoertner, Jun 19 2003 One more term from Herman Jamke (hermanjamke(AT)fastmail.fm), Dec 30 2007 a(22) - a(23) from Robert Price, Oct 17 2012 a(24) from Robert Price, Jan 18 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 14 04:44 EDT 2019. Contains 327995 sequences. (Running on oeis4.)