A010039 High-temperature expansion of Ising model susceptibility chi_2 for square lattice.

1, 4, 24, 208, 2208, 28864, 440064, 7752448, 153604608, 3398247424, 82812002304, 2208100261888, 63835179614208, 1991789102301184, 66630050985836544, 2381273427126550528, 90474637735806763008, 3643995535114567942144, 154996077159081295478784, 6946094284451252292026368

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Comments

It appears that a(n) is divisible by 2^n, and a(2n) is additionally divisible by 3. - Ralf Stephan, Aug 04 2013

Links

• Laurent Pierre, Bernard Bernu and Laura Messio, High temperature series expansions of S = 1/2 Heisenberg spin models: Algorithm to include the magnetic field with optimized complexity, SciPost Phys. 17, 105 (2024); arXiv:2404.02271 [cond-mat.str-el], 2024. See the supporting file SquareIsing_18_1.py; multiply pol1[1] by 2 to get this sequence.
• M. Lüscher and P. Weisz, Application of the linked cluster expansion to the n-component phi^4 theory, Nuclear Physics B 300 (1988), 325-359.

Crossrefs

Cf. A002906, A010040 (cubic), A010042 (mu_2), A010045 (chi_4), A005401 (Heisenberg).

Formula

E.g.f.: F(tanh(x)), where F(x) is the g.f. of A002906. - Andrey Zabolotskiy, Nov 19 2024

Extensions

Name clarified, terms a(15) and beyond using data from A002906 added by Andrey Zabolotskiy, Nov 25 2024