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.

A277661 1st-order coefficients of the 1/N-expansion of traces of negative powers of real Wishart matrices with parameter c=2.

Original entry on oeis.org

0, 0, 2, 18, 128, 840, 5306, 32802, 200064, 1209168, 7261042, 43394802, 258401216, 1534310232, 9089538922, 53748310338, 317337926144, 1871206403232, 11021718519266, 64859423566290, 381371547195648, 2240888478928488, 13159108981577242, 77232197285953890, 453066998085075840, 2656691258873376240
Offset: 0

Views

Author

Fabio Deelan Cunden, Oct 26 2016

Keywords

Comments

These numbers provide the 1st order of the 1/N-expansion of traces of powers of a random time-delay matrix in presence of time-reversal symmetry. (The 0th order is given by the Large Schröder numbers A006318.)

Links

Crossrefs

Cf. A006318 (0th order), A277662 (2nd order), A277663 (3rd order), A277664 (4th order), A277665 (5th order).

Programs

  • Mathematica
    CoefficientList[Series[(1 - 3 x)/(2 (x^2 - 6 x + 1)) - 1/(2 (x^2 - 6 x + 1)^(1/2)), {x, 0, 25}], x] (* Michael De Vlieger, Oct 26 2016 *)

Formula

G.f.: (1-3*x)/(2*(x^2-6*x+1))-1/(2*(x^2-6*x+1)^(1/2)).
a(n) ~ 2^(-5/2) * (3*sqrt(2)-4) * (1+sqrt(2))^(2*n+2) * (1 - 1/(sqrt(Pi*(3*sqrt(2)-4)*n))). - Vaclav Kotesovec, Oct 27 2016

Extensions

More terms from Michael De Vlieger, Oct 26 2016

A277663 3rd-order coefficients of the 1/N-expansion of traces of negative powers of real Wishart matrices with parameter c=2.

Original entry on oeis.org

0, 0, 10, 378, 7048, 96000, 1092460, 11060700, 103150528, 905077728, 7576640950, 61098854454, 477942694136, 3645484792560, 27220292840440, 199588002587160, 1440630859132416, 10256896070590464, 72150109176698562, 502120765832371602, 3461203073248719400, 23654601049848668256
Offset: 0

Views

Author

Fabio Deelan Cunden, Oct 26 2016

Keywords

Comments

These numbers provide the 3rd order of the 1/N-expansion of traces of powers of a random time-delay matrix in presence of time-reversal symmetry. (The 0th order is given by the Large Schröder numbers A006318.)

Links

Crossrefs

Cf. A006318 (0th order), A277661 (1st order), A277662 (2nd order), A277664 (4th order), A277665 (5th order).

Programs

  • Mathematica
    CoefficientList[Series[-(2 x) (2 x^3 - 9 x^2 + 19 x + 3) / ((x^2 - 6 x + 1)^(7/2)) - (2 x) (6 x^4 - 5 x^3 + 9 x^2 - 15 x - 3) / ((x^2 - 6 x + 1)^4), {x, 0, 25}], x] (* Vincenzo Librandi, Nov 07 2016 *)

Formula

G.f.: -(2*z)*(2*z^3-9*z^2+19*z+3)/(y(z)^(7/2))-(2*z)*(6*z^4-5*z^3+9*z^2-15*z-3)/(y(z)^4) where y(z)=z^2-6*z+1.
a(n) ~ (17*sqrt(2)/24-1) * n^3 * (1+sqrt(2))^(2*n+6) * (1 - (7*sqrt((8+6*sqrt(2)) / Pi))/(8*sqrt(n))). - Vaclav Kotesovec, Oct 27 2016

A277664 4th-order coefficients of the 1/N-expansion of traces of negative powers of real Wishart matrices with parameter c=2.

Original entry on oeis.org

0, 0, 22, 1638, 47454, 904530, 13529862, 172576362, 1966038698, 20583987894, 201838423616, 1878183167916, 16744919877108, 144061342087884, 1202594886126228, 9783039293041644, 77823360967288812, 607079393002409364, 4654603707195506610, 35144449267872359562, 261740341786424075106
Offset: 0

Views

Author

Fabio Deelan Cunden, Oct 26 2016

Keywords

Comments

These numbers provide the 4th order of the 1/N-expansion of traces of powers of a random time-delay matrix in presence of time-reversal symmetry. (The 0th order is instead given by the Large Schröder numbers A006318.)

Links

Crossrefs

Cf. A006318, A277661, A277662, A277663, A277665.

Programs

  • Mathematica
    y[z] := z^2 - 6*z + 1; CoefficientList[Series[(2*(36*z^7 + 20*z^6 + 24*z^5 - 219*z^4 + 216*z^3 + 163*z^2 + 6*z))/(y[z]^(11/2)) + (2*(12*z^8 - 132*z^7 + 618*z^6 - 1830*z^5 + 1840*z^4 + 720*z^3 - 134*z^2 - 6*z))/(y[z]^6), {z, 0, 50}],z] (* G. C. Greubel, Jan 29 2017 *)

Formula

G.f.: (2*(36*z^7+20*z^6+24*z^5-219*z^4+216*z^3+163*z^2+6*z))/(y(z)^(11/2)) +(2*(12*z^8-132*z^7+618*z^6-1830*z^5+1840*z^4+720*z^3-134*z^2-6*z))/(y(z)^6), where y(z)= z^2-6*z+1.
a(n) ~ 37 * (3*sqrt(2)+4)^(11/2) * n^(9/2) * (1+sqrt(2))^(2*n-8) / (9 * 2^(19/2) * sqrt(Pi)) * (1 - 12*sqrt(2*Pi*(4+3*sqrt(2)))/(37*sqrt(n))). - Vaclav Kotesovec, Oct 27 2016

Extensions

More terms from Michel Marcus, Nov 01 2016

A277665 5th-order coefficients of the 1/N-expansion of traces of negative powers of real Wishart matrices with parameter c=2.

Original entry on oeis.org

0, 0, 42, 6426, 291696, 7786680, 152881422, 2451889734, 34052988736, 424606263984, 4868397305884, 52193110266396, 529596113392928, 5132630490667056, 47846123752559076, 431382289963465044, 3778388016547646976, 32265703705734047808, 269434703704642529046, 2205554182120984631622
Offset: 0

Views

Author

Fabio Deelan Cunden, Oct 26 2016

Keywords

Comments

These numbers provide the 5th order of the 1/N-expansion of traces of powers of a random time-delay matrix in presence of time-reversal symmetry. (The 0th order is given by the Large Schröder numbers A006318.)

Links

Crossrefs

Cf. A006318 (0th order), A277661 (1st order), A277662 (2nd order), A277663 (3rd order), A277664 (4th order).

Programs

  • Mathematica
    y[z] := z^2 - 6*z + 1; CoefficientList[Series[-(2*z*(96*z^7 - 456*z^6 + 2992*z^5 - 7068*z^4 + 3089*z^3 + 8214*z^2 + 979*z + 12))/(y[z]^(13/2)) - (2*z*(288*z^8 + 776*z^7 - 336*z^6 - 2916*z^5 + 6276*z^4 - 1312*z^3 - 7560*z^2 - 964*z - 12))/(y[z]^7), {z,0,50}], z] (* G. C. Greubel, Jan 29 2017 *)

Formula

G.f.: -(2*z*(96*z^7 - 456*z^6 + 2992*z^5 - 7068*z^4 + 3089*z^3 + 8214*z^2 + 979*z + 12)) / (y(z)^(13/2)) - (2*z*(288*z^8 + 776*z^7 - 336*z^6 - 2916*z^5 + 6276*z^4 - 1312*z^3 - 7560*z^2 - 964*z - 12)) / (y(z)^7), where y(z) = z^2-6*z+1.

Extensions

More terms from Michel Marcus, Oct 30 2016

A277660 2nd-order coefficients of the 1/N-expansion of traces of negative powers of complex Wishart matrices with parameter c=2.

Original entry on oeis.org

0, 0, 2, 30, 310, 2730, 21980, 167076, 1220100, 8650620, 59958030, 408172050, 2738441706, 18151701750, 119100934680, 774719545320, 5001728701800, 32081745977496, 204596905143930, 1298154208907430, 8199305968563710, 51576591659861730, 323239814342259892, 2019025558874685900
Offset: 0

Views

Author

Fabio Deelan Cunden, Oct 26 2016

Keywords

Comments

These numbers provide the 2nd order of the 1/N-expansion of traces of powers of a random time-delay matrix without time-reversal symmetry. (The 0th order is instead given by the Large Schröder numbers A006318.)

Links

Crossrefs

Cf. A001850, A002695, A277661, A277662, A277663, A277664, A277665.

Programs

  • Maple
    a := proc(n) option remember; if n = 1 then 0 elif n = 2 then 2 else (3*(2*n - 1)*a(n-1) - (n + 1)*a(n-2))/(n - 2) fi; end:
seq(a(n), n = 1..25); # Peter Bala, Sep 28 2024
  • Mathematica
    a[n_] := If[n<2, 0, 2 GegenbauerC[n-2, 5/2, 3]]; a /@ Range[0, 20] (* Andrey Zabolotskiy, Oct 27 2016 *)
CoefficientList[Series[(2 x^2) / (x^2 - 6 x + 1)^(5/2), {x, 0, 25}], x] (* Vincenzo Librandi, Oct 30 2016 *)
  • PARI
    x='x+O('x^50); concat([0,0], Vec((2*x^2)/(x^2-6*x+1)^(5/2))) \\ G. C. Greubel, Jun 05 2017

Formula

G.f.: (2*x^2)/(x^2-6*x+1)^(5/2).
a(n) = 2*C_(n-2)^(5/2)(3) for n >= 2, where C_n^(m)(x) is the Gegenbauer polynomial. - Andrey Zabolotskiy, Oct 26 2016
a(n) ~ (1 + sqrt(2))^(2*n+1) * n^(3/2) / (3*2^(13/4)*sqrt(Pi)). - Vaclav Kotesovec, Oct 27 2016, simplified Aug 27 2025
From Peter Bala, Sep 20 2024: (Start)
a(n) = (1/6) * Sum_{k = 0..n} k*(k - 1)*binomial(n, k)*binomial(n+k, k).
a(n) = (1/12)*n*(n + 1)*(n - 1)*(n + 2)*hypergeom([n+3, -n+2], [3], -1).
a(n) = (2/3) * d^2/dx^2(Legendre_P(n, x)) at x = 3.
a(n) = (1/12)*n*(n + 1)*A001850(n) - (1/2)*A002695(n).
P-recursive: (n - 2)*a(n) = 3*(2*n - 1)*a(n-1) - (n + 1)*a(n-2) with a(1) = 0 and a(2) = 2. (End)

Extensions

a(9)-a(22) from Andrey Zabolotskiy, Oct 26 2016
a(23) from Fabio Deelan Cunden, Oct 29 2016
Showing 1-5 of 5 results.

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