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A131353 Consecutive prime pairs which after concatenation are prime (ascending order). +0
1
23, 3137, 8389, 151157, 157163, 167173, 199211, 233239, 257263, 263269, 271277, 331337, 353359, 373379, 433439, 467479, 509521, 523541, 541547, 601607, 653659, 661673, 677683, 727733, 941947, 971977, 10131019, 10331039, 11811187, 11871193 (list; graph; listen)
OFFSET

1,1

COMMENT

For the range above, such primes appear after a mean of 7.125 trials. Some concatenated primes are interlocking, such as 151157 and 157163.

FORMULA

Select consecutive prime pairs, concatenate, and test for primality

EXAMPLE

a(2) is 3137 because 31 and 37 are consecutive primes, and after concatenation 3137 is also prime

CROSSREFS

Adjacent sequences: A131350 A131351 A131352 this_sequence A131354 A131355 A131356

Sequence in context: A068655 A088385 A030461 this_sequence A136363 A134798 A103443

KEYWORD

easy,nonn,base

AUTHOR

Enoch Haga (Enokh(AT)comcast.net), Sep 30 2007

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Last modified May 16 23:01 EDT 2008. Contains 139884 sequences.


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