cp's OEIS Frontend

A120701 Number of unit circles which fit touching a circle of radius n-1, i.e., with their centers on a circle of radius n.

%I A120701 #25 Aug 26 2023 02:52:58
%S A120701 2,6,9,12,15,18,21,25,28,31,34,37,40,43,47,50,53,56,59,62,65,69,72,75,
%T A120701 78,81,84,87,91,94,97,100,103,106,109,113,116,119,122,125,128,131,135,
%U A120701 138,141,144,147,150,153,157,160,163,166,169,172,175,179,182,185,188
%N A120701 Number of unit circles which fit touching a circle of radius n-1, i.e., with their centers on a circle of radius n.
%C A120701 Coincides with A022844 = floor(n*Pi) except at n=1, 25510582, ... (sequence A120702).
%H A120701 G. C. Greubel, <a href="/A120701/b120701.txt">Table of n, a(n) for n = 1..10000</a>
%F A120701 a(n) = floor(Pi/arcsin(1/n)).
%t A120701 Table[Floor[Pi/ArcSin[1/n]], {n, 60}] (* _Indranil Ghosh_, Jul 21 2017 *)
%o A120701 (Python)
%o A120701 from mpmath import mp, pi, asin
%o A120701 mp.dps=100
%o A120701 def a(n): return int(floor(pi/asin(1./n)))
%o A120701 print([a(n) for n in range(1, 61)]) # _Indranil Ghosh_, Jul 21 2017
%o A120701 (SageMath) [floor(pi/arcsin(1/n)) for n in range(1,71)] # _G. C. Greubel_, Aug 25 2023
%o A120701 (Magma) R:= RealField(30); [Floor(Pi(R)/Arcsin(1/n)) : n in [1..70]]; // _G. C. Greubel_, Aug 25 2023
%Y A120701 Cf. A001116, A002486, A022844, A120702.
%K A120701 easy,nonn
%O A120701 1,1
%A A120701 _Martin Fuller_, Jun 28 2006