%I A146307
%S A146307 2,1,2,4,10,1,14,8,6,5,22,4,26,7,10,16,34,3,38,20,14,11,46,8,50,13,18,
%T A146307 28,58,5,62,32,22,17,70,12,74,19,26,40,82,7,86,44,30,23,94,16,98,25,34,
%U A146307 52,106,9,110,56,38,29,118,20,122,31,42,64,130,11,134,68,46,35,142,24
%N A146307 a(n) = denominator of (n-6)/(2n)=denominator of (n+6)/(2n)
%C A146307 For numerators see A146306.
%C A146307 General formula (*Artur Jasinski*):
%C A146307 2 Cos[2*Pi/n] = Hypergeometric2F1[(n-6)/(2n),(n+6)/(2n),1/2,3/4] =
%C A146307 Hypergeometric2F1[A146306(n)/a(n),A146306(n+12)/a(n),1/2,3/4].
%C A146307 2 Cos[2*Pi/n] is root of polynomial of degree = EulerPhi[n]/2 = A000010(n)/
               2 = A023022(n).
%C A146307 Records in this sequence are even and are congruent to 2 or 10 mod 12 
               (see A091999).
%C A146307 Indices where odd numbers occured in this seuqnce are 4n-2 (see A016825). 
               Indices where prime numbers occured in this sequence see A146309.
%t A146307 Table[Denominator[(n - 6)/(2 n)], {n, 1, 100}] (*Artur Jasinski*)
%Y A146307 A007310, A051724, A146306, A146308
%Y A146307 Sequence in context: A024959 A029728 A135547 this_sequence A063894 A024500 
               A000087
%Y A146307 Adjacent sequences: A146304 A146305 A146306 this_sequence A146308 A146309 
               A146310
%K A146307 nonn
%O A146307 1,1
%A A146307 Artur Jasinski (grafix(AT)csl.pl), Oct 29 2008