login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons 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
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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.

LINKS

Table of n, a(n) for n=1..25.

EXAMPLE

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

CROSSREFS

Cf. A164987.

Sequence in context: A049443 A228473 A156118 * A177811 A341118 A129242

Adjacent sequences:  A171655 A171656 A171657 * A171659 A171660 A171661

KEYWORD

nonn,base

AUTHOR

Ki Punches, Dec 14 2009

EXTENSIONS

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

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 1 08:54 EDT 2021. Contains 346385 sequences. (Running on oeis4.)