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#13 by Joerg Arndt at Fri Oct 13 07:37:11 EDT 2023
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#12 by Michel Marcus at Fri Oct 13 00:19:17 EDT 2023
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#11 by Pontus von Brömssen at Thu Oct 12 16:06:59 EDT 2023
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#10 by Pontus von Brömssen at Thu Oct 12 15:55:47 EDT 2023
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| NAME
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Beginning with 3, a(i)*a(j) + 2 is prime for all i,, j, i<>j.
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| COMMENTS
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From 2nd termAll onwards, terms have the form 10k10*k+3, 10*k+5 , or 10k10*k+7. Conjecture: sequence. [Corrected by _Pontus von Brömssen_, Oct is12 finite.2023]
Conjecture: sequence is finite.
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| EXAMPLE
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3*7 ++2, 5*7+2, 3*5+2, etc. are primes.
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| CROSSREFS
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Cf. A083519.
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| KEYWORD
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nonn,more
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| STATUS
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approved
editing
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#9 by R. J. Mathar at Mon Aug 25 11:59:19 EDT 2014
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#8 by R. J. Mathar at Mon Aug 25 11:59:16 EDT 2014
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| AUTHOR
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Amarnath Murthy and Meenakshi Srikanth (amarnathmenakan_murthys(AT)yahoo.com), May 05 2003
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| STATUS
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approved
editing
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#7 by N. J. A. Sloane at Thu Dec 05 20:08:01 EST 2013
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| AUTHOR
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_Amarnath Murthy _ and Meenakshi Srikanth (amarnath_murthy(AT)yahoo.com), May 05 2003
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Discussion
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| Thu Dec 05
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| OEIS Server: https://oeis.org/edit/global/2078
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#6 by Russ Cox at Sat Mar 31 13:20:47 EDT 2012
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| COMMENTS
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Next term is > 266*10^9. - . - _David Wasserman (wasserma(AT)spawar.navy.mil), _, Nov 22 2004
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| EXTENSIONS
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More terms from _David Wasserman (wasserma(AT)spawar.navy.mil), _, Nov 22 2004
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Discussion
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| Sat Mar 31
| 13:20
| OEIS Server: https://oeis.org/edit/global/880
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#5 by N. J. A. Sloane at Wed Dec 06 03:00:00 EST 2006
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| EXAMPLE
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3*7 +2, 5*7+2, 3*5+2, etc. are primeprimes.
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| KEYWORD
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nonn,new
nonn
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#4 by N. J. A. Sloane at Sun Feb 20 03:00:00 EST 2005
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| DATA
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3, 5, 7, 27, 45, 495, 3615, 16695, 533445, 832305, 122789427, 8705408757, 77597861913
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| OFFSET
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01,1
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| COMMENTS
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From 2nd term onwards, terms have the form a(n) = 10k+5 or 10k+7. Conjecture: sequence is finite.
Next term is > 266*10^9. - David Wasserman (wasserma(AT)spawar.navy.mil), Nov 22 2004
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| KEYWORD
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hard,more,nonn,new
nonn
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| EXTENSIONS
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More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Nov 22 2004
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