A171658 Primes ending with the digits 21 which are the only primes in their century.

155921, 5649221, 6726821, 8598221, 8825321, 9953621, 10303721, 11948021, 12117121, 14645921, 14821721, 14866421, 15275021, 17270621, 17524921, 18497321, 19193921, 19731821, 20741621, 21721621, 22170221, 23009521, 24257921, 24579221, 24919721

Offset: 1

Author

Ki Punches, Dec 14 2009

Keywords

• nonn
• base

Comments

Primes of the form 100*k+21 with no other prime of the form 100*k+j for j=1 to 99 with the same k.

Thanks for the assistance and research of John Moyer. There is likely an infinite number of such primes.

Examples

			a(1)=155921 is prime and it is the only prime between 155900 and 156000.
		

Crossrefs

Cf. A164987.

Extensions

Definition detailed and more terms appended by R. J. Mathar, Oct 09 2010