A344212 Decimal expansion of 1 + 1/sqrt(5).

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

Offset: 1

Author

Wesley Ivan Hurt, May 11 2021

Keywords

• nonn
• cons

Comments

Decimal expansion of the midradius of a rhombic triacontahedron with unit edge length.

Essentially the same sequence of digits as A176453, A134974, A020762 and A010476. - R. J. Mathar, May 16 2021

Examples

			1.447213595499957939281834733746255247088123671922305...
		

Links

• Wikipedia, Rhombic triacontahedron.
• Index entries for algebraic numbers, degree 2.

Crossrefs

Cf. A019952 (rhombic triacontahedron inscribed sphere radius).

Cf. A344171 (rhombic triacontahedron surface area).

Cf. A344172 (rhombic triacontahedron volume).

Cf. A010476, A020762, A081005, A134974, A176453, A187798, A242671.

Programs

Mathematica

RealDigits[1 + 1/Sqrt[5], 10, 100][[1]] // Flatten

PARI

5^-.5+1 \\ Charles R Greathouse IV, Feb 04 2025

PARI

polrootsreal(5*x^2-10*x+4)[2] \\ Charles R Greathouse IV, Feb 04 2025

Formula

From Amiram Eldar, Nov 28 2024: (Start)

Equals 2*A242671 = 1/A187798.

Equals Product_{k>=0} (1 + 1/A081005(k)). (End)