A098028 Smallest prime p such that p-2 is a product of exactly n distinct primes.

5, 17, 107, 1367, 15017, 285287, 6561557, 179444267, 3234846617, 100280245067, 3710369067407, 196649560572467, 8309321386330967, 307444891294245707, 24615215445537161447, 961380175077106319537, 78523577350789412776937

Offset: 1

Author

Lekraj Beedassy, Sep 10 2004

Keywords

• nonn
• hard

Examples

			1367 is the 4th term in the sequence because it is followed by primes 1997, 2417, 3137, 3257, ... with the property 1367-2 = 3*5*7*13, 1997-2 = 3*5*7*19, 2417-2 = 3*5*7*23, 3137-2 = 3*5*11*19, 3257-2 = 3*5*7*31, ...
		

Programs

Mathematica

Do[s = 3; While[ ! (Length[FactorInteger[Prime[s] - 2]] == n && Max[Last /@ FactorInteger[Prime[s] - 2]] == 1), s++ ]; Print[Prime[s]], {n, 1, 8}] (* Ryan Propper, Sep 01 2005 *)
With[{pn=PrimeNu[Prime[Range[11*10^6]]-2]},Prime[#]&/@Flatten[Table[ Position[ pn,n,{1},1],{n,8}]]] (* The program takes some time to generate the first 8 terms of the sequence *) (* Harvey P. Dale, Jan 18 2016 *)

Extensions

Extended by Ray Chandler, Sep 18 2004

One more term from Ryan Propper, Sep 01 2005

More terms from Don Reble, Apr 03 2006