A242671 Decimal expansion of k2, a Diophantine approximation constant such that the area of the "critical parallelogram" (in this case a square) is 4*k2.

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

Offset

0,1

Comments

Quoting Steven Finch: "The slopes of the 'critical parallelogram' are (1+sqrt(5))/2 [phi] and (1-sqrt(5))/2 [-1/phi]."

Essentially the same as A229780, A134972, A134945, A098317 and A002163. - R. J. Mathar, May 23 2014

Let W_n be the collection of all binary words of length n that do not contain two consecutive 0's. Let r_n be the ratio of the total number of 1's in W_n divided by the total number of letters in W_n. Then lim_{n->infinity} r_n = 0.723606... Equivalently, lim_{n->oo} A004798(n)/(n*A000045(n+2)) = 0.723606... - Geoffrey Critzer, Feb 04 2022

References

Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 2.23, p. 176.

Links

Table of n, a(n) for n=0..99.

Formula

Equals (1 + 1/sqrt(5))/2.

Equals 1/A094874. - Michel Marcus, Dec 01 2018

From Amiram Eldar, Feb 11 2022: (Start)

Equals phi/sqrt(5), where phi is the golden ratio (A001622).

Equals lim_{k->oo} Fibonacci(k+1)/Lucas(k). (End)

Example

k2 = 0.723606797749978969640917366873127623544...

Mathematica

RealDigits[(1+1/Sqrt[5])/2, 10, 100] // First

Crossrefs

Cf. A000032, A000045, A001622, A004798, A020762, A094214, A094874.

Sequence in context: A092234 A160101 A210975 * A065476 A019945 A335825

Adjacent sequences: A242668 A242669 A242670 * A242672 A242673 A242674

Keyword

nonn,cons

Author

Jean-François Alcover, May 20 2014

Status

approved