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 1-7 of 7 results.

A137514 A triangular sequence from umbral calculus expansion of Simon Plouffe's rational polynomial for A002890: p(x,t) = exp(x*t)*(1 - 6*t + 9*t^2 - 4*t^3 + t^4)/(4*t - 1)/(2*t - 1).

Original entry on oeis.org

1, 0, 1, 2, 0, 1, 12, 6, 0, 1, 120, 48, 12, 0, 1, 1680, 600, 120, 20, 0, 1, 31680, 10080, 1800, 240, 30, 0, 1, 766080, 221760, 35280, 4200, 420, 42, 0, 1, 22579200, 6128640, 887040, 94080, 8400, 672, 56, 0, 1, 778014720, 203212800, 27578880, 2661120, 211680, 15120, 1008, 72, 0, 1
Offset: 1

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Author

Roger L. Bagula, Apr 23 2008

Keywords

Comments

Row sums:
{1, 1, 3, 19, 181, 2421, 43831, 1027783, 29698089, 1011695401, 39319102891}
The t's here are actually Sqrt[] of the variables that give Gamma(1,t) in the Hill reference and is the expansion of Plouffe's rational polynomial for A002890. So this result is related closely to Hill's Gamma(x,y) and seems to be a generalization of the A002890 polynomial.

Examples

			Triangle begins:
  {1},
  {0, 1},
  {2, 0, 1},
  {12, 6, 0, 1},
  {120, 48, 12, 0, 1},
  {1680, 600, 120, 20, 0, 1},
  {31680, 10080, 1800, 240, 30, 0, 1},
  {766080, 221760, 35280, 4200, 420, 42, 0, 1},
  {22579200, 6128640, 887040, 94080, 8400, 672, 56, 0, 1},
  {778014720, 203212800, 27578880, 2661120, 211680, 15120, 1008, 72, 0, 1},
  ...
		

References

  • Terrel L. Hill, Statistical Mechanics: Principles and Selected Applications, Dover, New York, 1956, page 336 ff

Crossrefs

Programs

  • Mathematica
    Clear[p, f, g] p[t_] = Exp[x*t]*(1 - 6*t + 9*t^2 - 4*t^3 + t^4)/(4*t - 1)/(2*t - 1); Table[ ExpandAll[n!*SeriesCoefficient[Series[p[t], {t, 0, 30}], n]], {n, 0, 10}] a = Table[ CoefficientList[n!*SeriesCoefficient[; FullSimplify[Series[p[t], {t, 0, 30}]], n], x], {n, 0, 10}]; Flatten[a]

Formula

p(x,t) = exp(x*t)*(1 - 6*t + 9*t^2 - 4*t^3 + t^4)/(4*t - 1)/(2*t - 1) = Sum_{n>=0} P(x,n)*t^n/n!; out_n,m=n!*Coefficients(P(x,n)).

A002891 Low temperature series for spin-1/2 Ising partition function on 3-dimensional simple cubic lattice.

Original entry on oeis.org

1, 0, 0, 1, 0, 3, -3, 15, -30, 101, -261, 807, -2308, 7065, -21171, 65337, -200934, 627249, -1962034, 6192066, -19610346, 62482527, -199807110, 641837193, -2068695927, 6691611633, -21710041944, 70645706963, -230488840446, 753903842400, -2471624380458, 8120879664294, -26736570257010
Offset: 0

Views

Author

N. J. A. Sloane, C. Vohwinkel

Keywords

References

  • 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. A002926 (ferromagnetic susceptibility), A002915 (antiferromagnetic susceptibility), A001393 (high-temperature), A002890 (square lattice), A002892 (f.c.c. lattice), A030045 (4D cubic), A030047 (5D cubic).

Extensions

Corrections and updates from Steven Finch
"Free energy" changed back to "partition function" (basically the exponential of the free energy) in the name by Andrey Zabolotskiy, Feb 12 2022
a(28)-a(32) added by Andrey Zabolotskiy, Jun 30 2022 using Andrén's data (see his Table 2, column a_n for the coefficients of the expansion of the logarithm of the g.f. of this sequence)

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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Author

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

A029872 Low temperature series for spin-1/2 Ising specific heat on 2D square lattice.

Original entry on oeis.org

16, 72, 288, 1200, 5376, 25480, 125504, 634608, 3269680, 17086168, 90282240, 481347152, 2585485504, 13974825960, 75941188736, 414593263952, 2272626444528, 12502223573304, 68996534259040, 381858968527680, 2118806030647328, 11783826597027256, 65674579024955904
Offset: 0

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Author

Keywords

References

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

Crossrefs

Cf. A002890 (partition function).
Equals A029873/4 or A029874*8.

Programs

  • Mathematica
    CoefficientList[Series[1/(Pi*x^2*(-1 + x^2)^2) * (-2*Pi*x*(1 + x)^2 - (1 + x)^4 * EllipticE[16*(-1 + x)^2*x/(1 + x)^4] + (1 + 30*x^2 + x^4) * EllipticK[16*(-1 + x)^2*x/(1 + x)^4]), {x, 0, 25}], x] (* Vaclav Kotesovec, Apr 28 2024 *)

Formula

G.f.: ((u^4 + 30*u^2 + 1) * K(x) / Pi - (u+1)^4 * E(x) / Pi - 2*u*(u+1)^2) / (u^2 * (u^2-1)^2) = 4 * (f(u) * (f'(u)/u + f''(u)) - (f'(u))^2) / f(u)^2, where f(u) is the g.f. of A002890, K(x) and E(x) are the complete elliptic integrals, x = 4*(1-u)*sqrt(u)/(1+u)^2. - Andrey Zabolotskiy, Feb 15 2022
a(n) ~ 2 * (1 + sqrt(2))^(2*n+4) / (Pi*n). - Vaclav Kotesovec, Apr 28 2024

Extensions

Terms a(18) and beyond from Andrey Zabolotskiy, Feb 15 2022

A370953 Numerators of coefficients of the partition function per spin, lambda (divided by 2), in the very high temperature region, expressed as a power series in the parameter K^2, for the spin-1/2 Ising model on square lattice.

Original entry on oeis.org

1, 1, 4, 77, 1009, 101627, 1302779, 2513121979, 11291682179, 1354947005798, 23064317580681848, 20189102649892270054, 776220757551441546419, 641273428219629914673014, 5433381672262390009892530636, 1399751922597075578762073697769
Offset: 0

Views

Author

N. J. A. Sloane, Mar 10 2024

Keywords

Crossrefs

See A370954 for denominators.

Programs

  • Mathematica
    CoefficientList[With[{nmax = 7}, Exp[-Log[2]/2 + 1/(2 Pi) Integrate[Log[Cosh[2k]^2 + Sqrt[Sinh[2k]^4 + 1 - 2 Sinh[2k]^2 Cos[2\[Theta]] + O[k]^(2nmax+1)]], {\[Theta], 0, Pi}] + O[k]^(2nmax+1)]], k][[;; ;; 2]] // Numerator (* Andrey Zabolotskiy, Mar 10 2024 *)
    CoefficientList[Cosh[2k] Exp[-x HypergeometricPFQ[{1, 1, 3/2, 3/2}, {2, 2, 2}, 16x] /. {x -> (Sinh[2k]/(2Cosh[2k]^2))^2}] + O[k]^32, k][[;; ;; 2]] // Numerator (* Andrey Zabolotskiy, Mar 13 2024, using the g. f. from Gandhimohan M. Viswanathan *)

Formula

a(n) / A370954(n) ~ c * 2^(2*n) / (n^3 * log(1 + sqrt(2))^(2*n)), where c = 0.15662885... - Vaclav Kotesovec, May 02 2024

Extensions

Terms a(5) and beyond from Andrey Zabolotskiy, Mar 10 2024

A370955 Coefficients of the partition function per spin, x(k) (divided by 2), in the low temperature region, expressed as a power series in the parameter k^2, for the spin-1/2 Ising model on square lattice.

Original entry on oeis.org

1, -1, -4, -29, -265, -2745, -30773, -364315, -4488749, -57020414, -741999700, -9845906898, -132774990781, -1814964497342, -25098172218816, -350548840292011, -4938909144117611, -70118741489312657, -1002259422501603334, -14412940220878338617, -208393139882994584383
Offset: 0

Views

Author

N. J. A. Sloane, Mar 10 2024

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Exp[-x HypergeometricPFQ[{1, 1, 3/2, 3/2}, {2, 2, 2}, 16 x]] + O[x]^20, x] (* Andrey Zabolotskiy, Mar 10 2024, using the g. f. from Gandhimohan M. Viswanathan *)

Formula

From Vaclav Kotesovec, Apr 28 2024: (Start)
a(n) ~ -c * 16^n / n^2, where c = 0.071286406...
Conjecture: c = exp(2*G/Pi)/(8*Pi) = 0.071286406674269408358123..., where G is the Catalan's constant A006752. (End)

Extensions

Terms a(6) and beyond from Andrey Zabolotskiy, Mar 10 2024

A260784 Coefficients in a certain low-temperature series expansion.

Original entry on oeis.org

0, 24, 1440, 181440, 43545600, 17882726400, 11333177856000, 10257397742592000, 12540115964952576000, 19887027595237490688000, 39679473692005106319360000, 97249082487667949725286400000, 287164491478121796028858368000000, 1005464789964467723115455053824000000
Offset: 1

Views

Author

N. J. A. Sloane, Aug 04 2015

Keywords

Crossrefs

Cf. A002890.

Programs

  • Maple
    A260784 := proc(n)
        local a,d1,d2,d3,d4,d33half ;
        a := 0 ;
        for d2 from 0 do
            if 2*d2 > n then
                break;
            end if;
            for d3 from 0 do
                if 2*d2 +3*d3 > n then
                    break;
                end if;
                for d4 from 0 do
                    if 2*d2 +3*d3+4*d4 > n then
                        break;
                    end if;
                    d1 := n-2*d2-3*d3-4*d4 ;
                    if d1 >= 0 and type(d1+d3,'even') then
                        d13half := (d1+d3)/2 ;
                        a := a+(d1+d2+d3+d4)!/d1!/d2!/d3!/d4!*(-1)^(d2+d3+d4-1)*2^d2
                            /(d1+d2+d3+d4)*binomial(d1+d3,d13half)^2 ;
                    end if;
                end do:
            end do:
        end do:
        a*n!/2 ;
    end proc:
    seq(A260784(2*n),n=1..15) ; # R. J. Mathar, Aug 27 2015
  • Mathematica
    "Listing 1" in Siudem et al. (2014) gives Mathematica code for the fractions a(n)/(2n)!.

Formula

a(n) ~ 2^(2*n) * (1 + sqrt(2))^(2*n) * n^(2*n - 5/2) / (sqrt(Pi) * exp(2*n)). - Vaclav Kotesovec, May 03 2024
Showing 1-7 of 7 results.