A114784 Smallest prime of the form: all twos followed by prime(n). a(n) > prime(n). 0 if no such prime exists.

0, 23, 0, 227, 211, 2213, 22222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222217, 2222219, 223, 229, 2222222222222222222222222231, 2237, 241, 2243, 22247

Offset: 1

Author

Amarnath Murthy, Nov 17 2005

Keywords

• base
• nonn

Comments

Prime(n) is all zeros followed by prime(n). This is all twos followed by prime(n). Conjecture: No term is zero except a(1) = a(3) = 0.

a(6) has not been proved prime, but it is a probable prime. - Joshua Zucker, May 06 2006

The 206-digit number 222...217 is, in fact, prime, as quickly confirmed by the Magma Calculator (http://magma.maths.usyd.edu.au/calc/). - Jon E. Schoenfield, Aug 24 2009

Examples

			a(6) = 2213, as 213 is composite prime(6) = 13.
		

Crossrefs

Cf. A114783.

Extensions

More terms from Joshua Zucker, May 06 2006

Edited by T. D. Noe, Oct 30 2008