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A068700
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The concatenation of n with n-1 and n with n+1 both yield primes (twin primes).
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0
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42, 78, 102, 108, 180, 192, 270, 300, 312, 330, 342, 390, 420, 522, 540, 612, 660, 822, 840, 882, 1002, 1140, 1230, 1272, 1482, 1542, 1632, 1770, 2100, 2190, 2682, 2742, 3072, 3198, 3408, 3642, 3828, 4242, 4452, 4572, 4740, 4788, 4998, 5622, 5718, 5832
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| 42 is a member as 4241 as well as 4243 are primes.
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PROG
| (PARI) for(n=2, 200, if(isprime(n*10^ceil(log(n-1)/log(10))+n-1)*isprime(n*10^ceil(log(n+1)/log(10))+n+1)==1, print1(n, ", ")))
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CROSSREFS
| Common terms of A030458 and A052089.
Sequence in context: A043769 A039525 A072326 * A135850 A153644 A172437
Adjacent sequences: A068697 A068698 A068699 * A068701 A068702 A068703
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KEYWORD
| base,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 04 2002
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EXTENSIONS
| More terms from Benoit Cloitre (benoit7848c(AT)orange.fr), Mar 09 2002
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