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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 * A347936 A347939 A177811

Adjacent sequences:  A171655 A171656 A171657 * A171659 A171660 A171661

KEYWORD

nonn,base

AUTHOR

Ki Punches, Dec 14 2009

EXTENSIONS

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

STATUS

approved

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Last modified September 26 05:28 EDT 2022. Contains 356986 sequences. (Running on oeis4.)