login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A171658 Primes ending with the digits 21 which are the only primes in their century. 0

%I #11 Jan 03 2022 20:43:01

%S 155921,5649221,6726821,8598221,8825321,9953621,10303721,11948021,

%T 12117121,14645921,14821721,14866421,15275021,17270621,17524921,

%U 18497321,19193921,19731821,20741621,21721621,22170221,23009521,24257921,24579221,24919721

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

%C 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.

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

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

%Y Cf. A164987.

%K nonn,base

%O 1,1

%A _Ki Punches_, Dec 14 2009

%E Definition detailed and more terms appended by _R. J. Mathar_, Oct 09 2010

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 18 13:50 EDT 2024. Contains 371780 sequences. (Running on oeis4.)