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Search: id:A103617
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| A103617 |
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Concatenations of pairs of primes that differ by 10^9. |
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2
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| 71000000007, 971000000097, 1031000000103, 1811000000181, 2231000000223, 2411000000241, 2711000000271, 3491000000349, 4091000000409, 4331000000433, 4391000000439, 6071000000607, 6131000000613, 7871000000787, 8291000000829
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Integers in this sequence can never be prime, as they are all multiples of 3. They can be semiprimes, as is the case for Prime(42) concatenated with Prime(50847544) = 1811000000181 = 3 x 603666666727.
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FORMULA
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a(n) = Concatenate(P, P+1000000000) iff P prime and P+1000000000 prime.
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EXAMPLE
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181 is prime, 181+10^9 = 1000000181 is prime, so their concatenation is an element of this sequence: 1811000000181. Coincidentally, prime(181)+10^9 = 1000001087 is also prime.
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CROSSREFS
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Cf. A000040, A001358, A023201, A100750, A103195, A103206, A104718, A104719, A103523, A103534, A103576.
Sequence in context: A017496 A017628 A139572 this_sequence A022252 A034653 A115538
Adjacent sequences: A103614 A103615 A103616 this_sequence A103618 A103619 A103620
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KEYWORD
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base,easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Mar 25 2005
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