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Search: id:A056206
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| A056206 |
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Smallest prime p such that p+2^n is also a prime. |
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+0
9
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| 3, 3, 3, 3, 5, 3, 3, 7, 11, 7, 5, 3, 17, 37, 3, 3, 29, 3, 53, 7, 17, 67, 11, 43, 41, 97, 29, 3, 11, 3, 11, 61, 17, 79, 53, 31, 29, 7, 23, 97, 71, 277, 29, 7, 59, 127, 5, 61, 191, 193, 101, 37, 5, 163, 3, 97, 131, 577, 131, 151, 197, 193, 29, 13, 131, 709, 3, 61, 29, 67, 11, 331
(list; graph; listen)
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OFFSET
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0,1
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FORMULA
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a(n)=Min{p|p+2^n=q, both p and q are primes}
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EXAMPLE
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n=9, 512+{2,3,5,7,11,...}={514,515,519,523,...}={2.257,5.103,11.47,3.173,523=prime,...}. The smallest suitable prime is 11 and it gives 523=512+11. So a(9)=11.
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CROSSREFS
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Cf. A056208.
Adjacent sequences: A056203 A056204 A056205 this_sequence A056207 A056208 A056209
Sequence in context: A006671 A046074 A068048 this_sequence A125713 A162220 A118911
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Oct 06 2000
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