cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A010571 High temperature expansion of -u/J in odd powers of v = tanh(J/kT), where u is energy per site of the spin-1/2 Ising model on cubic lattice with nearest-neighbor interaction J at temperature T.

Original entry on oeis.org

3, 12, 120, 1368, 18300, 268728, 4179852, 67767744, 1133826324, 19443072084, 340085761968, 6046276240668, 108970501777080, 1986820814551056, 36587507853481908, 679619087721892176, 12720247240214281860, 239685390231729125004, 4543441582487318876664
Offset: 1

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Crossrefs

Formula

Sum_{n>=1} a(n) * v^(2*n-1) = v*q/2 + (1-v^2) * f'(v) / f(v), where f(v) = Sum_{n>=0} A001393(n) * v^(2*n) and q = 6 is the number of nearest neighbors. - Andrey Zabolotskiy, Feb 14 2022

Extensions

New name from Andrey Zabolotskiy, Jan 14 2019
a(7) corrected and more terms added by Andrey Zabolotskiy, Feb 14 2022

A002908 High temperature expansion of -u/J in odd powers of v = tanh(J/kT), where u is energy per site of the spin-1/2 Ising model on square lattice with nearest-neighbor interaction J at temperature T.

Original entry on oeis.org

2, 4, 8, 24, 84, 328, 1372, 6024, 27412, 128228, 613160, 2985116, 14751592, 73825416, 373488764, 1907334616, 9820757380, 50934592820, 265877371160, 1395907472968, 7366966846564, 39062802311672, 208015460898924, 1112050252939612, 5966352507546872
Offset: 1

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Comments

Previous name was: Energy function for square lattice.

References

  • C. Domb, Ising model, in Phase Transitions and Critical Phenomena, vol. 3, ed. C. Domb and M. S. Green, Academic Press, 1974; p. 386.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Maple
    series((1+v^2)*(1-(2/Pi)*(1-6*v^2+v^4)*EllipticK(4*v*(1-v^2)/(1+v^2)^2)/(1+v^2)^2)/2*v,v,50); # Sean A. Irvine, Nov 26 2017
  • Mathematica
    u[h_]:=Coth[2h](1+(2/Pi)(2Tanh[2h]^2-1)EllipticK[(2Sinh[2h]/Cosh[2h]^2)^2]);
    Table[SeriesCoefficient[u[ArcTanh[v]],{v,0,2n-1}],{n,10}]
    (* Andrey Zabolotskiy, Sep 12 2017; see Onsager's eq. (116) *)
    Rest[CoefficientList[Series[(1+x)/2 - (1 - 6*x + x^2)*EllipticK[(16*(-1 + x)^2*x)/(1 + x)^4] / (Pi*(1+x)), {x, 0, 25}], x]] (* Vaclav Kotesovec, Apr 27 2024 *)

Formula

a(n) ~ 2 * (1 + sqrt(2))^(2*n-1) / (Pi * n^2). - Vaclav Kotesovec, Apr 27 2024

Extensions

More terms and new name from Andrey Zabolotskiy, Oct 19 2017

A010572 High-temperature coefficients for the internal energy for spin-1/2 Ising model on 4-d cubic lattice.

Original entry on oeis.org

4, 24, 432, 10512, 290552, 8800432, 284289160, 9621738448
Offset: 0

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Crossrefs

Cf. A010571 (3D), A010573 (5D), A010574 (6D), A030044 (partition function), A010557 (fourth-field derivative of free energy), A010563.

Formula

Sum_{n>=0} a(n) * v^(2*n+1) = v*q/2 + (1-v^2) * f'(v) / f(v), where f(v) = Sum_{n>=0} A030044(n) * v^(2*n) and q = 8 is the number of nearest neighbors. - Andrey Zabolotskiy, Feb 16 2022

Extensions

a(5)-a(7) from Andrey Zabolotskiy, Feb 16 2022, corrected Nov 26 2024

A030049 High temperature series for spin-1/2 Ising partition function on 6D simple cubic lattice.

Original entry on oeis.org

1, 0, 15, 350, 13380, 664566
Offset: 0

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Keywords

References

  • S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 391-406.

Crossrefs

Cf. A010574 (internal energy), A010580 (susceptibility); A001393 (3D cubic lattice), A030044 (4D), A030048 (5D).

Extensions

"Free energy" corrected to "partition function" (basically the exponential of the free energy) in the name by Andrey Zabolotskiy, Feb 12 2022
a(5) added using data from A010574 by Andrey Zabolotskiy, Jan 20 2023
Showing 1-4 of 4 results.