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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 March 4 23:31 EST 2024. Contains 370537 sequences. (Running on oeis4.)