cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

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

Original entry on oeis.org

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

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Author

Ki Punches, Dec 14 2009

Keywords

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

A258275 a(n) = smallest number k > n such that the interval k*100 to k*100+99 has exactly the same prime pattern as the interval n*100 to n*100+99 (or 0 if no such term is known).

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4812895043702, 0, 38905562023, 0, 2406071834559, 0, 834998571515, 15367548589719, 274894696197322, 0, 3339850458, 0, 0, 90345210525, 127636130731, 0, 0, 7916673590887, 498009080381, 1128063679395, 616923037, 301998772331
Offset: 1

Views

Author

Tim Johannes Ohrtmann, Jun 25 2015

Keywords

Examples

			a(13) = 38905562023 because the primes between 1300 and 1399 are 1301, 1303, 1307, 1319, 1321, 1327, 1361, 1367, 1373, 1381 and 1399 and 38905562023 is the least century>13 that has exactly the same prime pattern: 3890556202301, 3890556202303, 3890556202307, 3890556202319, 3890556202321, 3890556202327, 3890556202361, 3890556202367, 3890556202373, 3890556202381, 3890556202399.
		

Crossrefs

Showing 1-2 of 2 results.