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Search: id:A007516
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| A007516 |
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(2^2^...^2) (n times) + 1.
(Formerly M2504)
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+0
4
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OFFSET
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0,2
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COMMENT
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a(0) could equally well be taken to be 2 rather than 1, which gives A004249. - N. J. A. Sloane, Sep 14 2009
The next term already has 19729 digits and is too large to include. - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Apr 14 2006
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
P. Ribenboim, The Book of Prime Number Records. Springer-Verlag, NY, 2nd ed., 1989, p. 73.
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FORMULA
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a(1) = 1, a(2) = 3, a(n+1) = 2^(a(n)-1)+1 - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Apr 14 2006
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MATHEMATICA
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a[1] := 1; a[2] := 3; a[n_] := 2^(a[n - 1] - 1) + 1; Table[a[n], {n, 1, 5}] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Apr 14 2006
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CROSSREFS
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Cf. A004249 (another version).
Sequence in context: A016045 A128336 A094487 this_sequence A039584 A136131 A143546
Adjacent sequences: A007513 A007514 A007515 this_sequence A007517 A007518 A007519
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com) and Robert G. Wilson v (rgwv(AT)rgwv.com)
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