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Search: id:A089793
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| A089793 |
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a(n) = the first prime in the earliest chain of 2n+1 consecutive primes whose sum is prime. |
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1
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| 2, 5, 5, 17, 3, 5, 29, 3, 3, 11, 7, 7, 5, 7, 13, 13, 7, 5, 5, 13, 7, 7, 7, 7, 11, 17, 3, 3, 97, 29, 3, 13, 3, 19, 19, 3, 5, 3, 23, 7, 11, 53, 31, 89, 53, 19, 11, 3, 17, 23, 83, 11, 5, 47, 37, 5, 17, 3, 3, 29, 23, 5, 5, 5, 59, 7, 7, 31, 3, 67, 3, 3, 89, 71, 31, 41, 29, 3, 17, 11, 7, 13, 13, 7
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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In general (except possibly when it begins with '2'), the sum of an even number of consecutive primes is even -hence the restriction to odd chain lengths.
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EXAMPLE
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17 is the first prime in the chain 17, 19, 23, 29, 31, 37, 41, which is the earliest chain of 2 * 3 + 1 = 7 consecutive primes whose sum, 197, is prime. Hence a(3) = 17.
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CROSSREFS
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Sequence in context: A121304 A002106 A064630 this_sequence A076570 A089121 A014442
Adjacent sequences: A089790 A089791 A089792 this_sequence A089794 A089795 A089796
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KEYWORD
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nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Jan 09 2004
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