%I M3509 #37 Aug 02 2024 22:39:16
%S 4,15,609,845029,1010073215739,1300459886313272270974271,
%T 1939680952094609786557359582286462958434022504402
%N Egyptian fraction for 1/ Pi.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H Vincenzo Librandi, <a href="/A006524/b006524.txt">Table of n, a(n) for n = 1..11</a> [a(11) corrected by _Georg Fischer_, Jun 04 2019]
%H H. P. Robinson, <a href="/A001466/a001466.pdf">Letter to N. J. A. Sloane, Sep 1975</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/EgyptianFraction.html">Egyptian Fraction</a>
%H <a href="/index/Ph#Pi314">Index entries for sequences related to the number Pi</a>
%H <a href="/index/Ed#Egypt">Index entries for sequences related to Egyptian fractions</a>
%t a = {}; k = N[1/Pi, 1000]; Do[s = Ceiling[1/k]; AppendTo[a, s]; k = k - 1/s, {n, 1, 10}]; a (* _Artur Jasinski_, Sep 22 2008 *)
%o (PARI) x = 1/Pi;
%o f(x, k) = if(k<1, x, f(x, k - 1) - 1/n(x, k));
%o n(x, k) = ceil(1/f(x, k - 1));
%o for(k = 1, 7, print1(n(x, k),", ")) \\ _Indranil Ghosh_, Mar 27 2017
%K nonn,frac
%O 1,1
%A _N. J. A. Sloane_, _Robert G. Wilson v_
%E More terms from _Herman P. Robinson_
%E Offset changed to 1 by _Indranil Ghosh_, Mar 27 2017