login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A245725 Decimal expansion of z_tri, a constant related to the enumeration of spanning trees on the triangular lattice (this is different from A242968). 6
1, 6, 1, 5, 3, 2, 9, 7, 3, 6, 0, 9, 7, 2, 5, 2, 5, 7, 0, 4, 6, 8, 1, 8, 2, 5, 5, 3, 6, 1, 9, 0, 3, 1, 9, 7, 0, 3, 6, 1, 2, 0, 9, 2, 0, 3, 9, 0, 2, 9, 3, 5, 0, 8, 0, 6, 5, 4, 3, 4, 2, 3, 5, 1, 8, 0, 5, 0, 7, 5, 5, 6, 4, 0, 3, 6, 3, 4, 9, 2, 1, 0, 4, 1, 8, 9, 3, 8, 0, 4, 5, 4, 4, 6, 8, 5, 6, 9, 6, 0, 3, 6, 7, 4 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.22 Lenz-Ising Constants, p. 400.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Robert Shrock and F. Y. Wu, Spanning Trees on Graphs and Lattices in d Dimensions p. 7.

FORMULA

log(2) + log(3) + H, where H is the auxiliary constant A242967.

EXAMPLE

1.6153297360972525704681825536190319703612092039029350806543423518...

MATHEMATICA

H = Sqrt[3]/(6*Pi)*PolyGamma[1, 1/6] - Pi/Sqrt[3] - Log[6]; RealDigits[Log[2] + Log[3] + H, 10, 104] // First

(* or *) 3*(Sqrt[3]/Pi)*N[Sum[1/n^2 - 1/(n+4)^2, {n, 1, Infinity, 6}], 104] // RealDigits // First

CROSSREFS

Cf. A242967, A242968, A242969.

Sequence in context: A010137 A245967 A212006 * A011096 A347177 A195695

Adjacent sequences:  A245722 A245723 A245724 * A245726 A245727 A245728

KEYWORD

nonn,cons,easy

AUTHOR

Jean-François Alcover, Jul 30 2014

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 28 09:03 EDT 2022. Contains 354112 sequences. (Running on oeis4.)