

A007516


(2^2^...^2) (n times) + 1.
(Formerly M2504)


4




OFFSET

0,2


COMMENTS

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, Apr 14 2006


REFERENCES

P. Ribenboim, The Book of Prime Number Records. SpringerVerlag, NY, 2nd ed., 1989, p. 73.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Table of n, a(n) for n=0..4.


FORMULA

a(1) = 1, a(2) = 3, a(n+1) = 2^(a(n)1) + 1.  Stefan Steinerberger, Apr 14 2006


MATHEMATICA

a[1] := 1; a[2] := 3; a[n_] := 2^(a[n  1]  1) + 1; Table[a[n], {n, 1, 5}] (* Stefan Steinerberger, Apr 14 2006 *)


CROSSREFS

Cf. A004249 (another version).
Sequence in context: A128336 A278735 A094487 * A249759 A039584 A191717
Adjacent sequences: A007513 A007514 A007515 * A007517 A007518 A007519


KEYWORD

nonn


AUTHOR

N. J. A. Sloane and Robert G. Wilson v


STATUS

approved



