A340052 -id:A340052 - cp's OEIS frontend

A007726 Number of spanning trees of quarter Aztec diamonds of order n.

1, 1, 4, 56, 2640, 411840, 210613312, 351102230528, 1901049105201408, 33349238079515381760, 1892086487183556298556416, 346728396311328694807284940800, 205021218459835103075295973360128000, 390870571052378289975757743555515137130496

Offset: 1

Richard Stanley

nonn

Mihai Ciucu (ciucu(AT)math.gatech.edu), in preparation, 2001.

Seiichi Manyama, Table of n, a(n) for n = 1..50
Timothy Y. Chow, The Q-spectrum and spanning trees of tensor products of bipartite graphs, Proc. Amer. Math. Soc. 125 (1997), no. 11, 3155-3161.
R. Kenyon, J. Propp and D. Wilson, Trees and matchings, Electronic Journal of Combinatorics, 7(1):R25, 2000.
D. E. Knuth, Aztec Diamonds, Checkerboard Graphs, and Spanning Trees, arXiv:math/9501234 [math.CO], 1995; J. Alg. Combinatorics 6 (1997), 253-257.
R. P. Stanley, Spanning trees of Aztec diamonds, Discrete Math. 157 (1996), 375-388 (Problem 251).
Index entries for sequences related to trees

Cf. A007725, A007341, A065072, A340052.

Table[Product[Product[4 - 2*Cos[j*Pi/n] - 2*Cos[k*Pi/n], {j, 1, k-1}], {k, 2, n-1}], {n, 1, 15}] // Round (* Vaclav Kotesovec, Dec 30 2020 *)
Table[Sqrt[Resultant[ChebyshevU[n-1, x/2], ChebyshevU[n-1, (4-x)/2], x] / (n * 2^(n-1))], {n, 1, 15}] (* Vaclav Kotesovec, Dec 30 2020 *)

default(realprecision, 120);
{a(n) = round(prod(j=2, n-1, prod(i=1, j-1, 4*sin(i*Pi/(2*n))^2+4*sin(j*Pi/(2*n))^2)))} \\ Seiichi Manyama, Dec 29 2020

a(n) = Product_{0Sean A. Irvine, Jan 20 2018
From Vaclav Kotesovec, Dec 30 2020: (Start)
a(n) ~ sqrt(Gamma(1/4)) * 2^(5/8) * exp(2*G*n^2/Pi) / (Pi^(3/8) * n^(3/4) * 2^(n/2) * (1 + sqrt(2))^n), where G is Catalan's constant A006752.
a(n) = sqrt(A007341(n) / (n * 2^(n-1))). (End)

More terms from Sean A. Irvine, Jan 20 2018

A127605 a(n) = 2^(2nn) * Product_{i=1..n} Product_{j=1..n} (sin(iPi/(2n+1))^2 + sin(jPi/(2n+1))^2).

Original entry on oeis.org

1, 6, 500, 463736, 4614756624, 485005220494432, 533978739649683515200, 6129678550595328659594928000, 731483813983605533022316212534132992, 905665520470954445892575061753881157482726912

Offset: 0

Miklos Kristof, Apr 03 2007

nonn

Cf. A004003, A007341, A340052.

for n from 0 to 12 do a[n]:=2^(2*n*n)*product(product(sin(i*Pi/(2*n+1))^2+ sin(j*Pi/(2*n+1))^2,j=1..n),i=1..n) od: seq(round(evalf(a[n],300)),n=0..12);

Table[(2*n+1) * 2^(n*(2*n-1)) * Product[Product[Sin[i*Pi/(2*n + 1)]^2 + Sin[j*Pi/(2*n + 1)]^2, {i, 1, j-1}], {j, 2, n}]^2, {n, 0, 15}] // Round (* Vaclav Kotesovec, Dec 30 2020 *)

a(n) ~ Gamma(1/4) * exp(G*(2*n+1)^2/Pi) / (2^(3/2) * Pi^(3/4) * sqrt(n)), where G is Catalan's constant A006752. - Vaclav Kotesovec, Dec 30 2020

A340185 Number of spanning trees in the halved Aztec diamond HOD_n.

Original entry on oeis.org

1, 1, 15, 2639, 5100561, 105518291153, 23067254643457375, 52901008815129395889375, 1266973371422697144030728637409, 315937379766837559600972497421046382689, 818563964325891485548944567913851815851212484079

Offset: 0

Seiichi Manyama, Dec 31 2020

nonn

                                              *
                                              |
                      *                   *---*---*
                      |                   |   |   |
      *           *---*---*           *---*---*---*---*
      |           |   |   |           |   |   |   |   |
  *---*---*   *---*---*---*---*   *---*---*---*---*---*---*
    HOD_1           HOD_2                   HOD_3
-------------------------------------------------------------
                  *
                  |
              *---*---*
              |   |   |
          *---*---*---*---*
          |   |   |   |   |
      *---*---*---*---*---*---*
      |   |   |   |   |   |   |
  *---*---*---*---*---*---*---*---*
                HOD_4

Seiichi Manyama, Table of n, a(n) for n = 0..40
Mihai Ciucu, Symmetry classes of spanning trees of Aztec diamonds and perfect matchings of odd squares with a unit hole, arXiv:0710.4500 [math.CO], 2007. See Corollary 3.7.

Cf. A004003, A007725, A007726, A065072, A127605, A340052, A340176 (halved Aztec diamond HMD_n).

Table[4^((n-1)*n) * Product[Product[(1 - Cos[j*Pi/(2*n + 1)]^2*Cos[k*Pi/(2*n + 1)]^2), {k, j+1, n}], {j, 1, n}], {n, 0, 12}] // Round (* Vaclav Kotesovec, Jan 03 2021 *)

default(realprecision, 120);
{a(n) = round(prod(j=1, 2*n, prod(k=j+1, 2*n-j, 4-4*cos(j*Pi/(2*n+1))*cos(k*Pi/(2*n+1)))))}

default(realprecision, 120);
{a(n) = round(4^((n-1)*n)*prod(j=1, n, prod(k=j+1, n, 1-(cos(j*Pi/(2*n+1))*cos(k*Pi/(2*n+1)))^2)))} \\ Seiichi Manyama, Jan 02 2021

# Using graphillion
from graphillion import GraphSet
def make_HOD(n):
    s = 1
    grids = []
    for i in range(2 * n + 1, 1, -2):
        for j in range(i - 2):
            a, b, c = s + j, s + j + 1, s + i + j
            grids.extend([(a, b), (b, c)])
        grids.append((s + i - 2, s + i - 1))
        s += i
    return grids
def A340185(n):
    if n == 0: return 1
    universe = make_HOD(n)
    GraphSet.set_universe(universe)
    spanning_trees = GraphSet.trees(is_spanning=True)
    return spanning_trees.len()
print([A340185(n) for n in range(7)])

a(n) = Product_{1<=j

From Seiichi Manyama, Jan 02 2021: (Start)

a(n) = 4^((n-1)*n) * Product_{1<=j

a(n) = A340052(n) * A065072(n) = (1/2^n) * sqrt(A127605(n) * A004003(n) / (2*n+1)). (End)

a(n) ~ sqrt(Gamma(1/4)) * exp(G*(2*n+1)^2/Pi) / (Pi^(3/8) * n^(3/4) * 2^(n + 3/4) * (1 + sqrt(2))^(n + 1/2)), where G is Catalan's constant A006752. - Vaclav Kotesovec, Jan 03 2021

A340396 a(n) = 2^(n^2 - 1) * Product_{j=1..n, k=1..n} (1 + sin(Pij/n)^2 + sin(Pik/n)^2).

Original entry on oeis.org

0, 1, 96, 93789, 1244160000, 241885578271872, 700566272328037500000, 30323548995402141685610526683, 19627362048402730985830806120284160000, 189995156103157091521654945902925881881155376920, 27506190205802587152768139358989866456457087869970721213256

Offset: 0

Vaclav Kotesovec, Jan 06 2021

nonn

Cf. A004003, A007726, A065072, A067518, A127605, A340052, A340165, A340182, A340183, A340293.

Table[2^(n^2 - 1) * Product[1 + Sin[Pi*j/n]^2 + Sin[Pi*k/n]^2, {j, 1, n}, {k, 1, n}], {n, 0, 10}] // Round

a(n) = 2^(n^2-1) * Product_{j=1..n, k=1..n} (3 - cos(Pi*j/n)^2 - cos(Pi*k/n)^2).
a(n) = 2^(n^2-1) * Product_{j=1..n, k=1..n} (2-cos(2*Pi*j/n)/2-cos(2*Pi*k/n)/2).
a(n) ~ 2^(n^2-1) * exp(4*c*n^2/Pi^2), where c = Integral_{x=0..Pi/2, y=0..Pi/2} log(1 + sin(x)^2 + sin(y)^2) dy dx = -Pi^2*(log(2) + log(sqrt(2)-1)/2) + Pi * Integral_{x=0..Pi/2} log(1 + sqrt(1 + 1/(1 + sin(x)^2))) dx = A340421 = 1.627008991085721315763766677017604437985734719035793082916212355323520649...

A340168 Decimal expansion of a constant related to the asymptotics of A004003.

Original entry on oeis.org

1, 1, 0, 8, 8, 6, 2, 2, 5, 8, 7, 8, 0, 7, 6, 7, 5, 1, 3, 2, 7, 6, 9, 5, 1, 1, 6, 2, 1, 3, 0, 8, 1, 9, 2, 9, 2, 6, 4, 5, 2, 6, 6, 1, 2, 6, 9, 6, 3, 5, 6, 9, 2, 2, 4, 3, 6, 2, 9, 4, 3, 1, 4, 1, 8, 4, 4, 7, 3, 5, 5, 6, 5, 3, 0, 9, 3, 4, 8, 6, 6, 3, 2, 1, 3, 4, 3, 9, 7, 1, 4, 6, 7, 5, 0, 7, 9, 0, 1, 5, 5, 7, 4, 0, 5

Offset: 1

Vaclav Kotesovec, Dec 30 2020

			1.1088622587807675132769511621308192926452661269635692243629431418447355653...

Cf. A004003, A007341, A007726, A065072, A127605, A340052.

RealDigits[2*E^(Catalan/Pi)/(1 + Sqrt[2]), 10, 110][[1]]

Equals lim_{n->infinity} A004003(n) / ((sqrt(2)-1)^(2*n) * exp(4*G*n*(n+1)/Pi)), where G is the Catalan's constant A006752.

Equals 2*exp(G/Pi) / (1 + sqrt(2)), where G is Catalan's constant A006752.

Showing 1-5 of 5 results.

cp's OEIS Frontend

A007726 Number of spanning trees of quarter Aztec diamonds of order n.

Views

Author

Keywords

References

Links

Crossrefs

Programs

Mathematica

PARI

Formula

Extensions

A127605 a(n) = 2^(2*n*n) * Product_{i=1..n} Product_{j=1..n} (sin(i*Pi/(2*n+1))^2 + sin(j*Pi/(2*n+1))^2).

Views

Author

Keywords

Crossrefs

Programs

Maple

Mathematica

Formula

A340185 Number of spanning trees in the halved Aztec diamond HOD_n.

Views

Author

Keywords

Comments

Links

Crossrefs

Programs

Mathematica

PARI

PARI

Python

Formula

A340396 a(n) = 2^(n^2 - 1) * Product_{j=1..n, k=1..n} (1 + sin(Pi*j/n)^2 + sin(Pi*k/n)^2).

Views

Author

Keywords

Crossrefs

Programs

Mathematica

Formula

A340168 Decimal expansion of a constant related to the asymptotics of A004003.

Views

Author

Keywords

Examples

Crossrefs

Programs

Mathematica

Formula

A127605 a(n) = 2^(2nn) * Product_{i=1..n} Product_{j=1..n} (sin(iPi/(2n+1))^2 + sin(jPi/(2n+1))^2).

A340396 a(n) = 2^(n^2 - 1) * Product_{j=1..n, k=1..n} (1 + sin(Pij/n)^2 + sin(Pik/n)^2).