OFFSET
1,3
COMMENTS
An algebraic integer of degree 4. - Charles R Greathouse IV, Nov 12 2014
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Jean-Paul Allouche, Henri Cohen, Michel Mendès France, and Jeffrey O. Shallit, De nouveaux curieux produits infinis, Acta Arithmetica, Vol. 49, No. 2 (1987), pp. 141-153; alternative link.
Simon Plouffe, 2^(1/4) or sqrt(sqrt(2)) to 20000 digits.
Simon Plouffe, 2^(1/4) to 1024 places.
Nikita Sidorov and Boris Solomyak, On the topology of sums in powers of an algebraic number, arXiv:0909.3324 [math.NT], 2009-2011.
David Terr and Eric W. Weisstein, Pisot Number.
FORMULA
Equals Product_{k>=0} (1 + (-1)^k/(4*k + 3)). - Amiram Eldar, Jul 25 2020
Equals Product_{k>=0} ((2*k+1)/(2*k+2))^(A000120(k)*(-1)^A000120(k)) (Allouche et al., 1987). - Amiram Eldar, Feb 04 2024
EXAMPLE
1.18920711...
MATHEMATICA
RealDigits[N[2^(1/4), 200]][[1]] (* Vladimir Joseph Stephan Orlovsky, Jan 24 2012 *)
PROG
(PARI) sqrtn(2, 4) \\ Charles R Greathouse IV, Apr 14 2014
(PARI) weber(I) \\ Charles R Greathouse IV, Feb 04 2015
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
STATUS
approved