A276780 - OEIS

%I #16 Jun 04 2023 12:01:47

%S 9,41,171,694,2790,11172,44702,178825,715319,2861297,11445210,

%T 45780865,183123485,301029988,301029988

%N a(n) = floor(log_10(1/error(n))), where error(n) is the error in the n-th iteration of the quartic Borwein-Borwein algorithm for computing 1/Pi.

%D J. M. Borwein and P. B. Borwein, Pi and the AGM, Wiley, 1987.

%H D. H. Bailey, J. M. Borwein, P. B. Borwein, and S. Plouffe, <a href="https://ntrs.nasa.gov/citations/19970009342">The Quest for Pi</a>, Mathematical Intelligencer, vol. 19, no. 1 (Jan. 1997), 50-57.

%H Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/A276780.py">Python program</a>.

%H Shalosh B. Ekhad, <a href="http://www.math.rutgers.edu/~zeilberg/mamarim/mamarimhtml/oJON1.html">Three New Sequences for the OEIS, in Fond Memory of Jon Borwein (1951-2016)</a>

%H Doron Zeilberger, <a href="http://www.math.rutgers.edu/~zeilberg/mamarim/mamarimhtml/JonBorwein.html">Jonathan Borwein (1951-2016), a PiONEER of Experimental Mathematics</a>, Experimental Mathematics Seminar, Rutgers University, Sep 15 2016.

%Y Cf. A276778, A276779.

%K nonn,hard,more

%O 1,1

%A _Doron Zeilberger_, Sep 18 2016

%E Revised definition and terms a(9)-a(15) from _Lucas A. Brown_, May 05 2023