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 1-10 of 13 results. Next

A008547 Erroneous version of A002906.

Original entry on oeis.org

12, 100, 1972, 5172, 34876, 89764, 229628, 1486308, 3763460, 9497380, 36212402548
Offset: 0

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Author

Marek Karliner (marek(AT)proton.tau.ac.il)

Keywords

References

  • C. Domb, "Ising Model", in "Phase Transitions and Critical Phenomena", Vol. 3, "Series Expansions for Lattice Models", edited by C. Domb and M.S. Green, Academic Press (1974).

A002931 Number of self-avoiding polygons of length 2n on square lattice (not allowing rotations).

Original entry on oeis.org

0, 1, 2, 7, 28, 124, 588, 2938, 15268, 81826, 449572, 2521270, 14385376, 83290424, 488384528, 2895432660, 17332874364, 104653427012, 636737003384, 3900770002646, 24045500114388, 149059814328236, 928782423033008, 5814401613289290, 36556766640745936
Offset: 1

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Keywords

Comments

Translations are allowed, but not rotations or reflections.
a(n) is also the coefficient of n^2 in the sequence of quadratic polynomials giving the numbers of 2k-cycles in the n X n grid graph for n >= k-1 (see the example). - Eric W. Weisstein, Apr 05 2018

Examples

			At length 8 there are 7 polygons, consisting of the 2, 1, 4 resp. rotations of:
._. .___. .___.
| | | . | | ._|
| | |___| |_|
|_|
Let p(k,n) be the number of 2k-cycles in the n X n grid graph for n >= k-1.  p(k,n) are quadratic polynomials in n, with the first few given by:
p(1,n) = 0,
p(2,n) = 1 - 2*n + n^2,
p(3,n) = 4 - 6*n + 2*n^2,
p(4,n) = 26 - 28*n + 7*n^2,
p(5,n) = 164 - 140*n + 28*n^2,
p(6,n) = 1046 - 740*n + 124*n^2,
p(7,n) = 6672 - 4056*n + 588*n^2,
p(8,n) = 42790 - 22904*n + 2938*n^2,
p(9,n) = 275888 - 132344*n + 15268*n^2,
...
The quadratic coefficients give a(n), so the first few are 0, 1, 2, 7, 28, 124, .... - _Eric W. Weisstein_, Apr 05 2018
		

References

  • N. Clisby and I. Jensen: A new transfer-matrix algorithm for exact enumerations: self-avoiding polygons on the square lattice, J. Phys. A: Math. Theor. 45 (2012). Also arXiv:1111.5877, 2011. [Extends sequence to a(65)]
  • I. G. Enting: Generating functions for enumerating self-avoiding rings on the square lattice, J. Phys. A: Math. Gen. 13 (1980). pp. 3713-3722. See Table 2.
  • A. J. Guttmann, Asymptotic analysis of power-series expansions, pp. 1-234 of C. Domb and J. L. Lebowitz, editors, Phase Transitions and Critical Phenomena. Vol. 13, Academic Press, NY, 1989.
  • B. D. Hughes, Random Walks and Random Environments, Oxford 1995, vol. 1, p. 461.
  • I. Jensen: A parallel algorithm for the enumeration of self-avoiding polygons on the square lattice, J. Phys. A: Math. Gen. 36 (2003). [Extends sequence to a(55)]
  • I. Jensen and A. J. Guttmann: Self-avoiding polygons on the square lattice, J. Phys. A: Math. Gen. 32 (1999). Also arXiv:cond-mat/9905291. [Extends sequence to a(45)]
  • 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. A056634, A036638, A036639. Equals A010566(n)/(4n).
Cf. A057730.
Cf. A302335 (constant coefficients in p(k,n)).
Cf. A302336 (linear coefficients in p(k,n)).

Extensions

Updated by N. J. A. Sloane, Mar 18 2021

A001334 Number of n-step self-avoiding walks on hexagonal [ =triangular ] lattice.

Original entry on oeis.org

1, 6, 30, 138, 618, 2730, 11946, 51882, 224130, 964134, 4133166, 17668938, 75355206, 320734686, 1362791250, 5781765582, 24497330322, 103673967882, 438296739594, 1851231376374, 7812439620678, 32944292555934, 138825972053046
Offset: 0

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Keywords

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

  • A. J. Guttmann, Asymptotic analysis of power-series expansions, pp. 1-234 of C. Domb and J. L. Lebowitz, editors, Phase Transitions and Critical Phenomena. Vol. 13, Academic Press, NY, 1989.
  • B. D. Hughes, Random Walks and Random Environments, Oxford 1995, vol. 1, p. 459.
  • 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

  • Mathematica
    mo={{2, 0},{-1, 1},{-1, -1},{-2, 0},{1, -1},{1, 1}}; a[0]=1;
    a[tg_, p_:{{0, 0}}] := Block[{e, mv = Complement[Last[p]+# & /@ mo, p]}, If[tg == 1, Length@mv, Sum[a[tg-1, Append[p, e]], {e, mv}]]];
    a /@ Range[0, 6]
    (* Robert FERREOL, Nov 28 2018; after the program of Giovanni Resta in A001411 *)
  • Python
    def add(L,x):
        M=[y for y in L];M.append(x)
        return(M)
    plus=lambda L,M : [x+y for x,y in zip(L,M)]
    mo=[[2,0],[-1,1],[-1, -1],[-2,0],[1,-1],[1, 1]]
    def a(n,P=[[0, 0]]):
        if n==0: return(1)
        mv1 = [plus(P[-1],x) for x in mo]
        mv2=[x for x in mv1 if x not in P]
        if n==1: return(len(mv2))
        else: return(sum(a(n-1,add(P,x)) for x in mv2))
    [a(n) for n in range(11)]
    # Robert FERREOL, Dec 11 2018

A002913 High temperature series for spin-1/2 Ising magnetic susceptibility on 3-dimensional simple cubic lattice.

Original entry on oeis.org

1, 6, 30, 150, 726, 3510, 16710, 79494, 375174, 1769686, 8306862, 38975286, 182265822, 852063558, 3973784886, 18527532310, 86228667894, 401225368086, 1864308847838, 8660961643254, 40190947325670, 186475398518726, 864404776466406, 4006394107568934, 18554916271112254, 85923704942057238
Offset: 0

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Author

Keywords

References

  • C. Domb, Ising model, in Phase Transitions and Critical Phenomena, vol. 3, ed. C. Domb and M. S. Green, Academic Press, 1974; p. 381.
  • 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. other quantities: A001393 (partition function), A010571 (internal energy), A002916 (specific heat), A003490 (surface susceptibility), A007287 (layer susceptibility), A010040, A010043, A010046.
Cf. other structures: A002906 (square), A002920 (hexagonal), A002910 (honeycomb), A002914 (b.c.c.), A002921 (f.c.c.), A003119 (diamond), A010556 (4D cubic), A010579 (5D cubic), A010580 (6D cubic), A030008 (7D cubic).
Cf. low-temperature series: A002926 (ferromagnetic), A002915 (antiferromagnetic).
Cf. other models: A002170 (Heisenberg), A003279 (spherical).

Extensions

Corrections and updates from Steven Finch
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Mar 01 2008
Several errors in the sequence were corrected by Per H. Lundow, Jan 17 2011

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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Author

Keywords

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

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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Keywords

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

A010556 High temperature series for spin-1/2 Ising magnetic susceptibility on 4D simple cubic lattice.

Original entry on oeis.org

1, 8, 56, 392, 2696, 18536, 126536, 863720, 5873768, 39942184, 271009112, 1838725896, 12457092504, 84392312392, 571140732808, 3865210690888, 26138072412040, 176752645426600, 1194553221342296, 8073068110703880, 54534614510976680
Offset: 0

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Author

Keywords

References

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

Crossrefs

Cf. A002906 (2D), A002913 (3D), A010579 (5D), A010580 (6D), A030008 (7D).

Extensions

a(17) corrected (was 176752645540264), a(18)-a(20) added using Butera & Pernici's formulas by Andrey Zabolotskiy, Aug 08 2022

A010579 High temperature series for spin-1/2 Ising magnetic susceptibility on 5D simple cubic lattice.

Original entry on oeis.org

1, 10, 90, 810, 7210, 64170, 568970, 5044810, 44649930, 395180650, 3494051130, 30893156970, 272971707930, 2411975074570, 21302972395370, 188151452434090, 1661273238131050, 14668124524584170, 129481802727508250, 1142991284620073450, 10087904498275867530
Offset: 0

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Author

Keywords

References

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

Crossrefs

Cf. A002906 (2D), A002913 (3D), A010556 (4D), A010580 (6D), A030008 (7D).

Extensions

Corrections and updates from Steven Finch
Terms a(16)-a(20) added using Butera & Pernici's formulas by Andrey Zabolotskiy, Aug 09 2022

A010580 High temperature series for spin-1/2 Ising magnetic susceptibility on 6D simple cubic lattice.

Original entry on oeis.org

1, 12, 132, 1452, 15852, 173052, 1884972, 20532252, 223437852, 2431526492, 26447593812, 287669976492, 3128064123732, 34013987172972, 369792173040492, 4020299656610636, 43702216875039660, 475060467524653980, 5163624600479230260, 56125562454502452780, 610010748386503122684
Offset: 0

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Author

Keywords

References

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

Crossrefs

Cf. A002906 (2D), A002913 (3D), A010556 (4D), A010579 (5D), A030008 (7D).

Extensions

Corrections and updates from Steven Finch
Terms a(16)-a(20) added using Butera & Pernici's formulas by Andrey Zabolotskiy, Aug 09 2022

A030008 High temperature series for spin-1/2 Ising magnetic susceptibility on 7D simple cubic lattice.

Original entry on oeis.org

1, 14, 182, 2366, 30590, 395486, 5105870, 65919182, 850586702, 10975573182, 141586912166, 1826501185054, 23558885899318, 303871575267918, 3919114007263518, 50545912921275198, 651868436561980638, 8406864950367314046, 108415583649894484278, 1398136240855886669662, 18029995593288775967598
Offset: 0

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Author

Keywords

References

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

Crossrefs

Cf. A002906 (2D), A002913 (3D), A010556 (4D), A010579 (5D), A010580 (6D).

Extensions

Terms a(16)-a(20) added using Butera & Pernici's formulas by Andrey Zabolotskiy, Aug 09 2022
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