A104954 Decimal expansion of the area of the regular triangle with circumradius 1.

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

Offset

1,2

Comments

Equivalently, the area in the complex plane of the smallest convex set containing all order-3 roots of unity.

Links

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

Eric Weisstein et al., Root of Unity.

Eric Weisstein's World of Mathematics, de Moivre Number.

Index entries for algebraic numbers, degree 2

Formula

Equals 3*sqrt(3)/4.

Equals (1/2)*A104956.

Example

1.299038105676657970145584756129404275207103940357785471...

Mathematica

RealDigits[N[Floor[n/2]*Sin[(2*Pi)/n] - Sin[(4*Pi*Floor[n/2])/n]/2 /. n -> 3, 108]][[1]]

Crossrefs

Cf. A104955, A104956, A104957.

Sequence in context: A198358 A145427 A348637 * A244292 A011072 A175295

Adjacent sequences: A104951 A104952 A104953 * A104955 A104956 A104957

Keyword

nonn,cons

Author

Joseph Biberstine (jrbibers(AT)indiana.edu), Mar 30 2005

Extensions

Edited by Georg Fischer, Jul 29 2021

Status

approved