login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A104954 Decimal expansion of the area of the regular 3-gon (triangle) of circumradius = 1. Note this is (1/2)*A104956. 4
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 (list; constant; graph; refs; listen; history; text; internal format)
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."

FORMULA

3*Sqrt[3]/4

EXAMPLE

1.2990381056766579701455847561294042752071039403577854710418552345889497626816000278108596400679364317567196060615550272724774588...

MATHEMATICA

Floor[n/2]*Sin[(2*Pi)/n] - Sin[(4*Pi*Floor[n/2])/n]/2 /. n -> 3

CROSSREFS

Cf. A104955, A104956, A104957.

Sequence in context: A073927 A198358 A145427 * A244292 A011072 A175295

Adjacent sequences:  A104951 A104952 A104953 * A104955 A104956 A104957

KEYWORD

nonn,cons

AUTHOR

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

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 26 05:37 EST 2020. Contains 331273 sequences. (Running on oeis4.)