OFFSET
1,2
COMMENTS
Decimal expansion of the shape of a (2/5)-extension rectangle; see A188640 for definitions of shape and r-extension rectangle. Briefly, shape=length/width, and an r-extension rectangle is composed of two rectangles of shape 1/r when r<1.
The continued fraction of the constant is 1, 4, 1, 1, 4, 1, ... = A146325.
FORMULA
Equals exp(arcsinh(1/5)). - Amiram Eldar, Jul 04 2023
EXAMPLE
1.219803902718556966005644821804556397912754189219919281516994...
MATHEMATICA
RealDigits[(1 + Sqrt[26])/5, 10, 111][[1]] (* Robert G. Wilson v, Aug 18 2011 *)
CROSSREFS
KEYWORD
AUTHOR
Clark Kimberling, Apr 09 2011
STATUS
approved