

A133986


Consecutive prime pairs which after concatenation are prime (ascending or descending order).


2



23, 53, 3137, 5347, 5953, 6761, 8389, 137131, 151157, 157163, 167173, 179173, 199211, 211199, 223211, 233239, 239233, 257263, 263257, 263269, 271277, 331337, 353359, 359353, 373379, 433439, 467479, 509521, 523541, 541523, 541547, 593587
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OFFSET

1,1


COMMENTS

For the range above the prime concatenations occur after a mean of 3.1579 trials. Some primes are interlocking, as many as three in succession.


LINKS

Table of n, a(n) for n=1..32.


FORMULA

Select consecutive prime pairs, concatenate and test for primality (ascending and descending order)


EXAMPLE

5347 is a member: 53 and 47, prime; 4753 was also tested, but is composite.


CROSSREFS

Cf. A088784.
Sequence in context: A078959 A238854 A045345 * A103006 A053236 A118603
Adjacent sequences: A133983 A133984 A133985 * A133987 A133988 A133989


KEYWORD

easy,nonn,base


AUTHOR

Enoch Haga, Sep 30 2007


EXTENSIONS

Edited by Charles R Greathouse IV, Apr 26 2010


STATUS

approved



