A147776 - OEIS

%I #6 Jan 02 2022 18:18:20

%S 5,9,9,9,7,7,9,6,7,0,2,2,5,8,8,3,8,6,0,8,7,5,9,5,3,5,2,4,5,9,2,0,6,0,

%T 3,5,5,0,0,3,2,8,9,7,0,0,5,1,7,8,1,0,6,9,7,3,5,6,1,5,8,4,4,7,5,0,5,8,

%U 6,9,2,2,4,8,5,7,7,0,9,0,4,3,4,0,3,0,8,6,3,9,7,0,6,7,2,8,8,4,7

%N Decimal expansion of z^(-3)+z^(-2)+z^(-1)+1+z+z^2+z^3, where z = exp(2*Pi*I/23).

%F 7 - 56*sin(Pi/23)^2 + 112*sin(Pi/23)^4 - 64*sin(Pi/23)^6. - _Charles R Greathouse IV_, Mar 25 2014

%e 5.9997796702258838608759535245920603550032897005178106973561...

%t RealDigits[Total[Re[Exp[(2 Pi I)/23]^Range[-3,3]]],10,120][[1]] (* _Harvey P. Dale_, Jan 02 2022 *)

%o (PARI) subst(Pol([-64,112,-56,7]),'x,sin(Pi/23)^2) \\ _Charles R Greathouse IV_, Mar 25 2014

%Y Cf. A147777.

%K nonn,cons

%O 1,1

%A _N. J. A. Sloane_, May 03 2009, based on a posting to the Number Theory List by Nigel Boston, Apr 29 2009