A068715 Primes of the form 10*3^k + 1.

11, 31, 271, 811, 21871, 196831, 5314411, 3874204891, 313810596091, 46383976865881019793281501678905914543189676980091, 2738927449953408337773479392637715347860807235997334411

Offset: 1

Author

Amarnath Murthy, Mar 05 2002

Keywords

• nonn

Examples

			21871 is a member as it is a concatenation of 2187 (= 3^7) and 1.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..19

Crossrefs

Cf. A068712, A068714.

Programs

Magma

[a: n in [0..200] | IsPrime(a) where a is 10*3^n + 1]; // Vincenzo Librandi, Dec 08 2011

Mathematica

Select[Table[10*3^n+1,{n,0,300}],PrimeQ](* Vincenzo Librandi, Dec 08 2011 *)

Extensions

More terms from Sascha Kurz, Mar 17 2002