cp's OEIS Frontend

A246730 Decimal expansion of r_9, the 9th smallest radius < 1 for which a compact packing of the plane exists, with disks of radius 1 and r_9.

%I A246730 #17 Feb 11 2025 09:14:49
%S A246730 6,3,7,5,5,5,9,7,7,2,3,1,9,4,5,7,9,3,4,9,1,3,1,7,1,6,7,7,3,9,9,0,9,5,
%T A246730 9,6,7,3,7,5,7,0,8,4,2,4,5,7,4,0,1,8,7,4,0,6,7,0,8,5,4,5,6,5,6,7,3,3,
%U A246730 1,8,1,1,5,9,9,4,0,6,8,7,3,7,5,7,5,0,4,1,7,1,6,6,0,0,7,3,3,3,7,7,4,9
%N A246730 Decimal expansion of r_9, the 9th smallest radius < 1 for which a compact packing of the plane exists, with disks of radius 1 and r_9.
%H A246730 Steven R. Finch, <a href="http://arxiv.org/abs/2001.00578">Errata and Addenda to Mathematical Constants</a>, p. 62.
%H A246730 <a href="/index/Al#algebraic_04">Index entries for algebraic numbers, degree 4</a>.
%F A246730 First root of x^4 - 10x^2 - 8x + 9.
%e A246730 0.637555977231945793491317167739909596737570842457401874067...
%t A246730 RealDigits[Root[x^4 - 10x^2 - 8x + 9, x, 1], 10, 102] // First
%o A246730 (PARI) polrootsreal(x^4-10*x^2-8*x+9)[1] \\ _Charles R Greathouse IV_, Feb 11 2025
%Y A246730 Cf. A246723 (r_1), A246724 (r_2), A246725 (r_3), A246726 (r_4), A246727 (r_5), A002193 (r_6 = sqrt(2)-1), A246728 (r_7), A246729 (r_8).
%K A246730 nonn,cons,easy
%O A246730 0,1
%A A246730 _Jean-François Alcover_, Sep 02 2014