Revision History for A103617
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#9 by Harvey P. Dale at Sat May 14 12:42:59 EDT 2022
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#8 by Harvey P. Dale at Sat May 14 12:42:53 EDT 2022
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| LINKS
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Harvey P. Dale, <a href="/A103617/b103617.txt">Table of n, a(n) for n = 1..1000</a>
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| STATUS
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approved
editing
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#7 by Harvey P. Dale at Sat May 14 12:41:49 EDT 2022
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#6 by Harvey P. Dale at Sat May 14 12:41:46 EDT 2022
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| MATHEMATICA
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FromDigits[Join[IntegerDigits[#], IntegerDigits[#+10^9]]]&/@Select[Prime[ Range[ 200]], PrimeQ[ #+ 10^9]&] (* Harvey P. Dale, May 14 2022 *)
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approved
editing
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#5 by Russ Cox at Fri Mar 30 18:40:27 EDT 2012
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| AUTHOR
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_Jonathan Vos Post (jvospost3(AT)gmail.com), _, Mar 25 2005
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Discussion
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| Fri Mar 30
| 18:40
| OEIS Server: https://oeis.org/edit/global/228
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#4 by N. J. A. Sloane at Fri Jan 09 03:00:00 EST 2009
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| KEYWORD
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base,easy,nonn,new
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| AUTHOR
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Jonathan Vos Post (jvospost2jvospost3(AT)yahoogmail.com), Mar 25 2005
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#3 by N. J. A. Sloane at Fri Feb 24 03:00:00 EST 2006
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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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| KEYWORD
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base,easy,nonn,new
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#2 by N. J. A. Sloane at Tue Jan 24 03:00:00 EST 2006
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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. CoincidentlyCoincidentally, prime(181)+10^9 = 1000001087 is also prime.
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| KEYWORD
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base,easy,nonn,new
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#1 by N. J. A. Sloane at Sat Apr 09 03:00:00 EDT 2005
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| NAME
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Concatenations of pairs of primes that differ by 10^9.
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| DATA
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71000000007, 971000000097, 1031000000103, 1811000000181, 2231000000223, 2411000000241, 2711000000271, 3491000000349, 4091000000409, 4331000000433, 4391000000439, 6071000000607, 6131000000613, 7871000000787, 8291000000829
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| OFFSET
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1,1
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| COMMENTS
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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. Coincidently, 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.
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| KEYWORD
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base,easy,nonn
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| AUTHOR
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Jonathan Vos Post (jvospost2(AT)yahoo.com), Mar 25 2005
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approved
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