A179050 Decimal expansion of 5/(2*sqrt(5+2*sqrt(5))), area of regular pentagram with base edge length 1.

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

Offset: 0

Author

Vladimir Joseph Stephan Orlovsky, Jun 26 2010

Keywords

• nonn
• cons
• easy

Comments

An algebraic number of degree 4: the smaller positive root of 16x^4 - 200x^2 + 125. - Charles R Greathouse IV, Dec 03 2012

Examples

			0.81229924058226581538967853053783616238725867880368775076951179784168...
		

Links

• Thomas M. Green, Area of Pentagram
• Index entries for algebraic numbers, degree 4

Crossrefs

Cf. A002194, A010502, A102771, A120011, A179047, A179048, A104956.

Programs

Mathematica

a=1;area=5/(2*Sqrt[5+2*Sqrt[5]]);RealDigits[N[area,20]]

PARI

5/sqrt(20+8*sqrt(5)) \\ Charles R Greathouse IV, Dec 03 2012

Extensions

Offset corrected, keyword:cons inserted by R. J. Mathar, Jun 28 2010

Name corrected by Charles R Greathouse IV, Dec 03 2012