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A119739
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Numbers n such that 7^n+3 is semiprime.
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0
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OFFSET
| 1,2
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COMMENTS
| Or (7^n+3)/2 is prime.
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EXAMPLE
| 7^1+3=19=2*5,
7^3+3=346=2*173,
7^31+3=2*78887691017422903307521373,
7^47+3=2*2621669158378151817230729359430975727773,
7^83+3=2*6951960974910262341699296037696359556850100616048572362472005937832173
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MATHEMATICA
| Do[ If[ PrimeQ[(7^n + 3)/2], Print@n], {n, 1, 11501, 2}] (* Robert G. Wilson v *)
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CROSSREFS
| Sequence in context: A177104 A078330 A107210 * A163579 A141966 A050833
Adjacent sequences: A119736 A119737 A119738 * A119740 A119741 A119742
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KEYWORD
| more,nonn,less
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AUTHOR
| Zak Seidov (zakseidov(AT)yahoo.com), Jun 14 2006
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EXTENSIONS
| a(6) from Robert G. Wilson v (rgwv(at)rgwv.com), Jun 14 2006
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