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Search: id:A156895
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| A156895 |
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Primes of the form prod{2^n + 1, [n=0,1,2,3...]} + 1. |
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+0
1
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| 3, 7, 31, 271, 4591, 151471, 9845551, 326409519151, 16455349947998422816223361143099916435126171767057238357700938736968751
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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10th term has 150 digits. [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 07 2009]
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EXAMPLE
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(2^0 + 1)*(2^1 + 1)*(2^2 + 1)*(2^3 + 1)*(2^4 + 1)= 2*3*5*9*17+ 1 = 4591
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MAPLE
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a := proc (n) if isprime(1+product(2^k+1, k = 0 .. n)) = true then 1+product(2^k+1, k = 0 .. n) else end if end proc: seq(a(n), n = 0 .. 40); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 07 2009]
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CROSSREFS
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Sequence in context: A030521 A105767 A063896 this_sequence A074047 A121810 A081475
Adjacent sequences: A156892 A156893 A156894 this_sequence A156896 A156897 A156898
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KEYWORD
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nonn
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AUTHOR
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J. M. Bergot (thekingfishb(AT)yahoo.ca), Feb 17 2009
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EXTENSIONS
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9th term added by Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 07 2009
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