OFFSET
0,4
REFERENCES
C. Domb, Ising model, in Phase Transitions and Critical Phenomena, vol. 3, ed. C. Domb and M. S. Green, Academic Press, 1974; p. 421.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
C. Domb, Ising model, Phase Transitions and Critical Phenomena 3 (1974), 257, 380-381, 384-387, 390-391, 412-423. (Annotated scanned copy)
Shigeo Naya, On the Spontaneous Magnetizations of Honeycomb and Kagomé Ising Lattices, Progress of Theoretical Physics, 11 (1954), 53-62.
FORMULA
G.f.: (1 - 16 * z^3 * (1+z^3) / ((1-z)^3 * (1-z^2)^3))^(1/8) [Shigeo Naya]. - Andrey Zabolotskiy, Jun 01 2022
a(n) ~ -Gamma(1/8) * sqrt(sqrt(2) - 1) * (2 + sqrt(3))^n / (2^(27/8) * 3^(1/16) * Pi * n^(9/8)). - Vaclav Kotesovec, Apr 27 2024
MATHEMATICA
CoefficientList[Series[(1 - 16 * x^3 * (1+x^3) / ((1-x)^3 * (1-x^2)^3))^(1/8), {x, 0, 30}], x] (* Vaclav Kotesovec, Apr 27 2024 *)
CROSSREFS
KEYWORD
sign,easy
AUTHOR
EXTENSIONS
Offset changed, signs of terms changed, and more terms added by Andrey Zabolotskiy, Jun 01 2022
STATUS
approved