%I #27 Jun 04 2023 12:01:08

%S 1,4,9,20,42,85,173,347,697,1395,2792,5587,11175,22352,44706,89414,

%T 178830,357661,715324,1430650,2861303,5722607,11445216,22890435,

%U 45780872,91561745,183123492,301029986,301029986

%N a(n) = floor(log_10(1/error(n))), where error(n) is the error in the n-th iteration of the Salamin-Brent algorithm for computing 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/A276778.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>; <a href="/A276778/a276778_1.pdf">Local copy, pdf file only, no active links</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; <a href="/A276778/a276778.pdf">Local copy, pdf file only, no active links</a>

%Y Cf. A276779, A276780.

%K nonn,hard,more

%O 1,2

%A _Doron Zeilberger_, Sep 18 2016

%E Revised definition and terms a(18)-a(29) from _Lucas A. Brown_, May 05 2023