A280819 Decimal expansion of 12*sin(Pi/12).

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

Offset

1,1

Comments

The ratio of the perimeter of a regular 12-gon (dodecagon) to its diameter (greatest diagonal).

A quartic integer: the least positive root of x^4 - 144x^2 + 1296.

Links

Table of n, a(n) for n=1..105.

Index entries for algebraic numbers, degree 4

Formula

12*A019824.

Example

3.105828541230249148186786051488579940188826815839166165768038487780683696...

Mathematica

First@ RealDigits@ N[12 Sin[Pi/12], 120] (* Michael De Vlieger, Feb 05 2017 *)

Prog

(PARI) 12*sin(Pi/12)
(PARI) polrootsreal(x^4-144*x^2+1296)[3] \\ Charles R Greathouse IV, Feb 05 2017

Crossrefs

Cf. For other n-gons: A010466 (n=4), 10*A019827 (n=5, 10), A280533 (n=7), A280585 (n=8), A280633 (n=9), A280725 (n=11).

Sequence in context: A110032 A201667 A175779 * A300280 A135670 A096754

Adjacent sequences: A280816 A280817 A280818 * A280820 A280821 A280822

Keyword

nonn,cons

Author

Rick L. Shepherd, Jan 08 2017

Status

approved