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 1-5 of 5 results.

A002927 Low temperature series for spin-1/2 Ising magnetic susceptibility on 2D square lattice.

Original entry on oeis.org

0, 0, 1, 8, 60, 416, 2791, 18296, 118016, 752008, 4746341, 29727472, 185016612, 1145415208, 7059265827, 43338407712, 265168691392, 1617656173824, 9842665771649, 59748291677832, 361933688520940, 2188328005246304, 13208464812265559, 79600379336505560, 479025509574159232
Offset: 0

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Comments

The zero-field susceptibility per spin is 4m^2/kT * Sum_{n >= 0} a(n) * u^n, where u = exp(-4J/kT). (m is the magnetic moment of a single spin; this factor may be present or absent depending on the precise definition of the susceptibility.) The b-file has been obtained from the series by Guttmann and Jensen via the substitution r = u/(1-u)^2 and dividing by 4. - Andrey Zabolotskiy, Feb 11 2022

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

Cf. A002906 (high-temperature), A002979 (antiferromagnetic susceptibility), A029872 (specific heat), A002928 (magnetization), A002890 (partition function), A047709 (hexagonal lattice), A002912 (honeycomb), A002926 (cubic lattice), A010115 (spin-1 Ising).

Formula

a(n) ~ c * n^(3/4) * (1 + sqrt(2))^(2*n), where c = 0.0187325517235678... - Vaclav Kotesovec, May 06 2024

Extensions

Corrections and updates from Steven Finch
a(0) = a(1) = 0 prepended, terms a(20) and beyond added by Andrey Zabolotskiy, Feb 10 2022

A010102 Spontaneous magnetization coefficients for square lattice spin 1 Ising model.

Original entry on oeis.org

1, 0, 0, 0, -1, 0, 0, -4, 3, 0, -30, 48, -52, -120, 368, -612, -254, 2524, -6216, 4040, 11805, -49400, 68268, 14928, -332511, 734508, -568038, -1641320, 6202774, -9239676, -2503162, 42749908, -99021392, 72255812, 215763902
Offset: 0

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Crossrefs

Extensions

Link corrected by Ralf Stephan, Aug 04 2013

A136264 Expansion of g.f. (1+x)^2*(x^2-6*x+1)/(x-1)^4.

Original entry on oeis.org

1, 0, -16, -64, -160, -320, -560, -896, -1344, -1920, -2640, -3520, -4576, -5824, -7280, -8960, -10880, -13056, -15504, -18240, -21280, -24640, -28336, -32384, -36800, -41600, -46800, -52416, -58464, -64960, -71920, -79360, -87296, -95744, -104720, -114240, -124320, -134976, -146224, -158080
Offset: 0

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Author

Roger L. Bagula, Apr 07 2008

Keywords

Comments

This g.f. is the eighth power of the spontaneous magnetization series for the two-dimensional square lattice in the parameter x = exp(-4J/kT), cf. A002928.

References

  • Terrel L. Hill, Statistical Mechanics: Principles and Selected Applications, Dover, New York, 1956, page 331. See eq. 44.12 for the g.f. with x replaced by x^2.

Crossrefs

Essentially the same as A102860. Cf. A115046, A002928.

Programs

  • Mathematica
    CoefficientList[Series[(1+x)^2(x^2-6x+1)/(x-1)^4,{x,0,40}],x] (* or *) LinearRecurrence[{4,-6,4,-1},{1,0,-16,-64,-160},40] (* Harvey P. Dale, Mar 15 2020 *)
  • PARI
    Vec((1+x)^2*(x^2-6*x+1)/(x-1)^4 + O(x^100)) \\ Altug Alkan, Oct 26 2015

Formula

a(n) = 8*n*(1 - n^2)/3, n>0. - R. J. Mathar, Mar 09 2009
E.g.f.: 1 - 8*exp(x)*x^2*(3 + x)/3. - Stefano Spezia, Oct 11 2023

A007206 Magnetization for honeycomb lattice.

Original entry on oeis.org

1, 0, 0, -2, -6, -18, -54, -168, -534, -1732, -5706, -19038, -64176, -218190, -747180, -2574488, -8918070, -31036560, -108457488, -380390574, -1338495492, -4723664566, -16714545822, -59286878556, -210755970528, -750721297056, -2679075662922, -9577156141654, -34290858526926, -122959225609518
Offset: 0

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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).

Crossrefs

Programs

  • 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 *)

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

Extensions

Offset changed, signs of terms changed, and more terms added by Andrey Zabolotskiy, Jun 01 2022

A007207 Magnetization for hexagonal lattice.

Original entry on oeis.org

1, 0, 0, -2, 0, -12, 2, -78, 24, -548, 228, -4050, 2030, -30960, 17670, -242402, 152520, -1932000, 1312844, -15612150, 11297052, -127551884, 97291026, -1051478274, 838994486, -8732657724, 7246304736, -72983051674, 62686156026, -613243234224, 543146222970
Offset: 0

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Comments

The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular 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. 421.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[(1 - 16 * x^3 / ((1+3*x) * (1-x)^3))^(1/8), {x, 0, 30}], x] (* Vaclav Kotesovec, Apr 27 2024 *)

Formula

G.f.: (1 - 16 * x^3 / ((1+3*x) * (1-x)^3))^(1/8) [Shigeo Naya]. - Andrey Zabolotskiy, Jun 01 2022
a(n) ~ (-1)^n * 3^n / (Gamma(1/8) * 2^(1/4) * n^(7/8)) * (1 - (-1)^n * sqrt(sqrt(2) - 1) * Gamma(1/8)^2 / (2^(13/4) * Pi * n^(1/4))). - Vaclav Kotesovec, Apr 27 2024

Extensions

Offset changed, signs of terms changed, and more terms added by Andrey Zabolotskiy, Jun 01 2022
Showing 1-5 of 5 results.