A002727 -id:A002727 - cp's OEIS frontend

A002728 Number of n X (n+2) binary matrices.

1, 4, 22, 190, 3250, 136758, 17256831, 7216495370, 10271202313659, 49856692830176512, 826297617412284162618, 46948445432190686211183650, 9200267975562856184153936960940, 6261904454889790650636380541051266410, 14910331834338546882501064075429145637985605

Offset: 0

N. J. A. Sloane

nonn

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).

Andrew Howroyd, Table of n, a(n) for n = 0..50 (terms 0..23 from Alois P. Heinz)
A. Kerber, Experimentelle Mathematik, Séminaire Lotharingien de Combinatoire. Institut de Recherche Math. Avancée, Université Louis Pasteur, Strasbourg, Actes 19 (1988), 77-83. [Annotated scanned copy]
B. Misek, On the number of classes of strongly equivalent incidence matrices, (Czech with English summary) Casopis Pest. Mat. 89 1964 211-218.

Cf. A002623, A002727, A006148, A002724, A002725.

A diagonal of the array A(m,n) described in A028657. - N. J. A. Sloane, Sep 01 2013

b:= proc(n, i) option remember; `if`(n=0, {0}, `if`(i<1, {},
      {seq(map(p-> p+j*x^i, b(n-i*j, i-1) )[], j=0..n/i)}))
    end:
a:= n-> add(add(2^add(add(igcd(i, j)* coeff(s, x, i)*
      coeff(t, x, j), j=1..degree(t)), i=1..degree(s))/
      mul(i^coeff(s, x, i)*coeff(s, x, i)!, i=1..degree(s))/
      mul(i^coeff(t, x, i)*coeff(t, x, i)!, i=1..degree(t)),
      t=b(n+2$2)), s=b(n$2)):
seq(a(n), n=0..12);  # Alois P. Heinz, Aug 01 2014

b[n_, i_] := b[n, i] = If[n == 0, {0}, If[i<1, {}, Table[Function[{p}, p + j*x^i]@ b[n-i*j, i-1] , {j, 0, n/i}]]] // Flatten; a[n_] := Sum[Sum[2^Sum[Sum[GCD[i, j]*Coefficient[s, x, i]*Coefficient[t, x, j], {j, 1, Exponent[t, x]}], {i, 1, Exponent[s, x]}]/Product[i^Coefficient[s, x, i]*Coefficient[s, x, i]!, {i, 1, Exponent[s, x]}]/Product[i^Coefficient[t, x, i]*Coefficient[t, x, i]!, {i, 1, Exponent[t, x]}], {t, b[n+2, n+2]}], {s, b[n, n]}]; Table[a[n], {n, 0, 12}] (* Jean-François Alcover, Nov 28 2014, after Alois P. Heinz *)

a(n) = A(n+2,n) \\ A defined in A028657. - Andrew Howroyd, Mar 01 2023

a(n) = sum {1*s_1+2*s_2+...=n, 1*t_1+2*t_2+...=n+2} (fix A[s_1, s_2, ...;t_1, t_2, ...]/(1^s_1*s_1!*2^s_2*s_2!*...*1^t_1*t_1!*2^t_2*t_2!*...)) where fix A[...] = 2^sum {i, j>=1} (gcd(i, j)*s_i*t_j). - Sean A. Irvine, Jul 31 2014

More terms from Vladeta Jovovic, Feb 04 2000

A005745 Number of n-covers of an unlabeled 3-set.

Original entry on oeis.org

1, 6, 23, 65, 156, 336, 664, 1229, 2159, 3629, 5877, 9221, 14070, 20951, 30530, 43634, 61283, 84725, 115461, 155294, 206368, 271210, 352784, 454550, 580509, 735280, 924163, 1153207, 1429292, 1760218, 2154776, 2622859, 3175555, 3825247

Offset: 1

N. J. A. Sloane, Simon Plouffe

Number of n X 3 binary matrices with at least one 1 in every column up to row and column permutations. - Andrew Howroyd, Feb 28 2023

R. J. Clarke, Covering a set by subsets, Discrete Math., 81 (1990), 147-152.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Andrew Howroyd, Table of n, a(n) for n = 1..1000
Vladeta Jovovic, Binary matrices up to row and column permutations

A diagonal of A055080.
First differences give A055609.
Cf. A002623, A002727.
Cf. A005744, A005746, A005747, A005748, A005771.

Vec(G(3, x) - G(2, x) + O(x^40)) \\ G defined in A028657. - Andrew Howroyd, Feb 28 2023

a(n) = A002727(n) - A002623(n).

G.f.: -x*(x^8-x^7-x^6-2*x^5+2*x^4+x^3-3*x^2-2*x-1)/((x^3-1)^2*(x^2-1)^2*(x-1)^4).

More terms from Vladeta Jovovic, May 26 2000

A005746 Number of n-covers of an unlabeled 4-set.

Original entry on oeis.org

1, 9, 51, 230, 863, 2864, 8609, 23883, 61883, 151214, 350929, 778113, 1656265, 3398229, 6743791, 12983181, 24311044, 44377016, 79124476, 138048542, 236050912, 396137492, 653285736, 1059923072, 1693592112, 2667563553, 4145373780, 6360553548, 9643151582

Offset: 1

N. J. A. Sloane, Simon Plouffe

Number of n X 4 binary matrices with at least one 1 in every column up to row and column permutations. - Andrew Howroyd, Feb 28 2023

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Colin Barker, Table of n, a(n) for n = 1..1000
R. J. Clarke, Covering a set by subsets, Discrete Math., 81 (1990), 147-152.
Vladeta Jovovic, Binary matrices up to row and column permutations

A diagonal of A055080.
First differences give A055082.
Cf. A002727, A006148.
Cf. A005744, A005745, A005747, A005748, A005771.

Rest@ CoefficientList[Series[x (1 + 3 x + 9 x^2 + 26 x^3 + 35 x^4 + 92 x^5 + 127 x^6 + 201 x^7 + 242 x^8 + 253 x^9 + 248 x^10 + 205 x^11 + 123 x^12 + 86 x^13 + 31 x^14 + 24 x^15 + 19 x^16 + 5 x^17 + 3 x^18 -
2 x^19 - 4 x^20 + 2 x^21 - 4 x^22 + 3 x^23 - x^25 + 2 x^26 - x^27)/((1 - x)^16 (1 + x)^6 (1 + x^2)^3 (1 + x + x^2)^4), {x, 0, 29}], x] (* Michael De Vlieger, Aug 23 2016 *)

Vec(x*(1 +3*x +9*x^2 +26*x^3 +35*x^4 +92*x^5 +127*x^6 +201*x^7 +242*x^8 +253*x^9 +248*x^10 +205*x^11 +123*x^12 +86*x^13 +31*x^14 +24*x^15 +19*x^16 +5*x^17 +3*x^18 -2*x^19 -4*x^20 +2*x^21 -4*x^22 +3*x^23 -x^25 +2*x^26 -x^27) / ((1 -x)^16*(1 +x)^6*(1 +x^2)^3*(1 +x +x^2)^4) + O(x^40)) \\ Colin Barker, Aug 23 2016

Vec(G(4, x) - G(3, x) + O(x^40)) \\ G defined in A028657. - Andrew Howroyd, Feb 28 2023

a(n) = A006148(n) - A002727(n).

G.f.: x*(1 +3*x +9*x^2 +26*x^3 +35*x^4 +92*x^5 +127*x^6 +201*x^7 +242*x^8 +253*x^9 +248*x^10 +205*x^11 +123*x^12 +86*x^13 +31*x^14 +24*x^15 +19*x^16 +5*x^17 +3*x^18 -2*x^19 -4*x^20 +2*x^21 -4*x^22 +3*x^23 -x^25 +2*x^26 -x^27) / ((1 -x)^16*(1 +x)^6*(1 +x^2)^3*(1 +x +x^2)^4). - Corrected by Colin Barker, Aug 23 2016

More terms and g.f. from Vladeta Jovovic, May 26 2000

a(19) onwards corrected by Sean A. Irvine, Aug 22 2016

A353585 Square array T(n,k): row n lists the number of inequivalent matrices over Z/nZ, modulo permutations of rows and columns, of size r X c, 1 <= r <= c, c >= 1.

Original entry on oeis.org

1, 1, 2, 1, 3, 3, 1, 7, 6, 4, 1, 4, 27, 10, 5, 1, 13, 10, 76, 15, 6, 1, 36, 92, 20, 175, 21, 7, 1, 5, 738, 430, 35, 351, 28, 8, 1, 22, 15, 8240, 1505, 56, 637, 36, 9, 1, 87, 267, 35, 57675, 4291, 84, 1072, 45, 10, 1, 317, 5053, 1996, 70, 289716, 10528, 120, 1701, 55, 11

Offset: 1

M. F. Hasler, Apr 28 2022

The array is read by falling antidiagonals.
Each row lists the number of inequivalent matrices of size 1 X 1, then 2 X 1, 2 X 2, then 3 X 1, 3 X 2, 3 X 3, etc., with coefficients in Z/nZ (or equivalently, in {1, ..., n}). See Examples for more.
Row 1 counts the zero matrices, there is only one of any size. Row 2 counts binary matrices, this is the lower triangular part of A028657, without the trivial row & column 0. (This table might have been extended with a trivial column 0 = A000012 (counting the 1 matrix of size 0) and row 0 = A000007 counting the number of r X c matrices with no entry, as done in A246106.)
The square matrices (size 1 X 1, 2 X 2, 3 X 3, ...) are counted in columns with triangular numbers, k = T(r) = r(r+1)/2 = (1, 3, 6, 10, 15, ...) = A000217.

			The table starts
   n \ k=1,  2,   3,   4,   5,   6, ...: T(n,k)
  ----+--------------------------------------
   1  |  1   1    1    1    1     1 ...
   2  |  2   3    7    4   13    36 ...
   3  |  3   6   27   10   92   738 ...
   4  |  4  10   76   20  430  8240 ...
   5  |  5  15  175   35 1505 57675 ...
  ...
Columns 2, 3 and 4, 5, 6 correspond to matrices of size 1 X 2, 2 X 2 and 1 X 3, 2 X 3, 3 X 3, respectively.
Column 4 says that there are (1, 4, 10, 20, 35, ...) inequivalent matrices of size 1 X 3 with entries in Z/nZ (n = 1, 2, 3, 4, ...); these numbers are given by (n+2 choose 3) = binomial(n+2, 3) = n(n+1)(n+2)/6 = A000292(n).

OEIS Index to number of inequivalent matrices modulo permutation of row and columns.

All of the following related sequences can be expressed in terms of T(n, k, r) := T(n, k(k-1)/2 + r), WLOG r <= k:
A028657(n,k) = A353585(2,n,k): inequivalent m X n binary matrices,
A002723(n) = T(2,n,2): size n X 2, A002724(n) = T(2,n,n): size n X n,
A002727(n) = T(2,n,3): size n X 3, A002725(n) = T(2,n,n+1): size n X (n+1),
A006148(n) = T(2,n,4): size n X 4, A002728(n) = T(2,n,n+2): size n X (n+2),
A052264(n) = T(2,n,5): size n X 5,
A052269(n) = T(3,n,n): number of inequivalent ternary matrices of size n X n,
A052271(n) = T(4,n,n): number of inequivalent matrices over Z/4Z of size n X n,
A052272(n) = T(5,n,n): number of inequivalent matrices over Z/5Z of size n X n,
A246106(n,k) = A353585(k,n,n): number of inequivalent n X n matrices over Z/kZ, and its diagonal A091058 and columns 1, 2, ..., 10: A000012, A091059, A091060, A091061, A091062, A246122, A246123, A246124, A246125, A246126.

A353585(n,k,r)={if(!r,r=sqrtint(8*k)\/2; k-=r*(r-1)\2); my(m(c, p=1, L=0)=for(i=1,#c, if(i==#c || c[i+1]!=c[i], p *= c[i]^(i-L)*(i-L)!; L=i )); p, S=0); forpart(P=k, my(T=0); forpart(Q=r, T += n^sum(i=1,#P, sum(j=1,#Q, gcd(P[i],Q[j]) ))/m(Q)); S += T/m(P)); S}

Let k = c(c-1)/2 + r, 1 <= r <= c, then
T(n, c, r) := T(n, k) = Sum_{p in P(c), q in P(r)} n^S(p, q)/(N(p)*N(q)), where P(r) are the partitions of r, S(p, q) = Sum_{i in p, j in q} gcd(i, j), N(p) = Product_{distinct parts x in p} x^m(x)*m(x)!, m(x) = multiplicity of x in p.
(See, e.g., A080577 for a list of partitions of positive integers.)
In particular:
T(n, 1) = n, T(n, 2) = n(n+1)/2 = A000217(n), T(n, 4) = C(n+2, 3) = A000292(n), T(n, 7) = C(n+3, 4) = A000332(n+3), etc.: T(n, k(k+1)/2 + 1) = C(n+k, k+1),
T(n, k(k+1)/2) = A246106(k, n).

A052267 Number of 2 X n matrices over GF(3) under row and column permutations.

Original entry on oeis.org

1, 6, 27, 92, 267, 678, 1561, 3312, 6582, 12372, 22194, 38232, 63594, 102564, 160974, 246576, 369567, 543114, 784069, 1113684, 1558557, 2151578, 2933151, 3952416, 5268796, 6953544, 9091668, 11783856, 15148836, 19325736, 24476940, 30790944, 38485773, 47812398

Offset: 0

Vladeta Jovovic, Feb 04 2000

Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (6,-12,2,27,-36,0,36,-27,-2,12,-6,1).

Cf. A002623, A002727.

Vec((3*x^2+1) / ((1-x^2)^3*(1-x)^6) + O(x^40)) \\ Colin Barker, Jan 16 2017

G.f.: (3*x^2+1) /((1-x^2)^3*(1-x)^6).

a(n) = ((315*(475+37*(-1)^n) + 6*(54959+945*(-1)^n)*n + (298618+630*(-1)^n)*n^2 + 150528*n^3 + 46788*n^4 + 9156*n^5 + 1092*n^6 + 72*n^7 + 2*n^8)) / 161280. - Colin Barker, Jan 16 2017

A055484 Number of unlabeled 3-element intersecting families (with not necessarily distinct sets) of an n-element set.

Original entry on oeis.org

1, 4, 14, 39, 96, 213, 437, 837, 1520, 2632, 4380, 7040, 10979, 16668, 24716, 35879, 51104, 71549, 98625, 134025, 179782, 238292, 312386, 405368, 521083, 663968, 839140, 1052439, 1310534, 1620985, 1992343, 2434229, 2957458, 3574108

Offset: 1

Vladeta Jovovic, Goran Kilibarda, Jul 03 2000

nonn

G. C. Greubel, Table of n, a(n) for n = 1..1000
V. Jovovic, G. Kilibarda, On the number of Boolean functions in the Post classes F^{mu}_8, (in Russian), Diskretnaya Matematika, 11 (1999), no. 4, 127-138.
V. Jovovic, G. Kilibarda, On the number of Boolean functions in the Post classes F^{mu}_8, (English translation), Discrete Mathematics and Applications, 9, (1999), no. 6.
Index entries for linear recurrences with constant coefficients, signature (4, -4, -2, 2, 4, 3, -12, 3, 4, 2, -2, -4, 4, -1).

Cf. A053155 (labeled case), A005783, A002727, A051180.

Rest[CoefficientList[Series[-x*(x^3 - x^2 - 1)*(x^6 + x^4 + 2*x^3 + x^2 + 1)/((x^3 - 1)^2*(x^2 - 1)^2*(x - 1)^4), {x, 0, 50}], x]] (* G. C. Greubel, Oct 06 2017 *)
LinearRecurrence[{4,-4,-2,2,4,3,-12,3,4,2,-2,-4,4,-1},{1,4,14,39,96,213,437,837,1520,2632,4380,7040,10979,16668},40] (* Harvey P. Dale, Jun 10 2024 *)

x='x+O('x^50); Vec(-x*(x^3-x^2-1)*(x^6+x^4+2*x^3+x^2+1)/( (x^3-1)^2*(x^2-1)^2*(x-1)^4)) \\ G. C. Greubel, Oct 06 2017

G.f.: -x*(x^3-x^2-1)*(x^6+x^4+2*x^3+x^2+1)/((x^3-1)^2*(x^2-1)^2*(x-1)^4).

More terms from James Sellers, Jul 04 2000

A056204 Number of n X 5 binary matrices under row and column permutations and column complementations.

Original entry on oeis.org

1, 1, 6, 16, 81, 299, 1358, 5567, 23350, 91998, 351058, 1269907, 4394634, 14495236, 45779246, 138567568, 403282017, 1130773069, 3062535192, 8028046724, 20411824364, 50429813556, 121280243676, 284360432241, 650972702410

Offset: 0

Vladeta Jovovic, Aug 05 2000

nonn

M. A. Harrison, On the number of classes of binary matrices, IEEE Trans. Computers, 22 (1973), 1048-1051.

Andrew Howroyd, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, order 148.

Column k=5 of A363349.

Cf. A005232, A006380, A006381, A006382, A002727, A006148, A052264.

G.f.: 1/3840*(1/(1 - x^1)^32 + 231/(1 - x^2)^16 + 20/(1 - x^1)^16/(1 - x^2)^8 + 520/(1 - x^4)^8 + 60/(1 - x^1)^8/(1 - x^2)^12 + 80/(1 - x^1)^8/(1 - x^3)^8 + 720/(1 - x^2)^4/(1 - x^6)^4 + 160/(1 - x^1)^4/(1 - x^2)^2/(1 - x^3)^4/(1 - x^6)^2 + 320/(1 - x^4)^2/(1 - x^12)^2 + 240/(1 - x^1)^4/(1 - x^2)^2/(1 - x^4)^6 + 480/(1 - x^8)^4 + 240/(1 - x^2)^4/(1 - x^4)^6 + 384/(1 - x^1)^2/(1 - x^5)^6 + 384/(1 - x^2)^1/(1 - x^10)^3).

A056205 Number of n X 6 binary matrices under row and column permutations and column complementations.

Original entry on oeis.org

1, 1, 7, 23, 153, 849, 6128, 43534, 319119, 2255466, 15307395, 98349144, 597543497, 3430839916, 18653684881, 96273409815, 473010823993, 2218614773950, 9961651259869, 42927432229913, 177963663264430

Offset: 0

Vladeta Jovovic, Aug 05 2000

nonn

M. A. Harrison, On the number of classes of binary matrices, IEEE Trans.Computers, 22 (1973), 1048-1051.

Andrew Howroyd, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, order 312.

Column k=6 of A363349.

Cf. A005232, A006380, A006381, A006382, A002727, A006148, A052264.

G.f.: 1/46080*(1/(1 - x^1)^64 + 1053/(1 - x^2)^32 + 30/(1 - x^1)^32/(1 - x^2)^16 + 4920/(1 - x^4)^16 + 180/(1 - x^1)^16/(1 - x^2)^24 + 120/(1 - x^1)^8/(1 - x^2)^28 + 160/(1 - x^1)^16/(1 - x^3)^16 + 5280/(1 - x^2)^8/(1 - x^6)^8 + 960/(1 - x^1)^8/(1 - x^2)^4/(1 - x^3)^8/(1 - x^6)^4 + 3840/(1 - x^4)^4/(1 - x^12)^4 + 640/(1 - x^1)^4/(1 - x^3)^20 + 1920/(1 - x^2)^2/(1 - x^6)^10 + 720/(1 - x^1)^8/(1 - x^2)^4/(1 - x^4)^12 + 5760/(1 - x^8)^8 + 2160/(1 - x^2)^8/(1 - x^4)^12 + 1440/(1 - x^1)^4/(1 - x^2)^6/(1 - x^4)^12 + 2304/(1 - x^1)^4/(1 - x^5)^12 + 6912/(1 - x^2)^2/(1 - x^10)^6 + 3840/(1 - x^1)^2/(1 - x^2)^1/(1 - x^3)^2/(1 - x^6)^9 + 3840/(1 - x^4)^1/(1 - x^12)^5).

A055194 Number of 3 X n binary matrices with distinct rows, up to row and column permutation; (n,3)-hypergraphs (including empty hyperedge but excluding multiple hyperedges).

Original entry on oeis.org

3, 16, 52, 134, 302, 614, 1159, 2064, 3504, 5716, 9018, 13818, 20643, 30158, 43190, 60758, 84110, 114746, 154469, 205422, 270132, 351562, 453172, 578962, 733551, 922238, 1151072, 1426932, 1757618, 2151920, 2619731, 3172138, 3821524, 4581682, 5467942, 6497272, 7688431

Offset: 2

Vladeta Jovovic, Jun 30 2000

Index entries for linear recurrences with constant coefficients, signature (4,-4,-2,2,4,3,-12,3,4,2,-2,-4,4,-1).

Cf. A002727.

G.f.: -x^2*(x^8-2*x^6-2*x^5+4*x^3-4*x-3)/((x^3-1)^2*(x^2-1)^2*(x-1)^4).

a(n) ~ n^7/30240. - Stefano Spezia, Nov 22 2023

More terms from James Sellers, Jul 04 2000

a(35)-a(38) from Stefano Spezia, Nov 22 2023

A058053 Number of 3-rowed binary matrices with n ones and no zero columns, up to row and column permutation.

Original entry on oeis.org

1, 1, 3, 6, 11, 18, 33, 49, 78, 117, 171, 242, 346, 469, 640, 855, 1127, 1463, 1896, 2405, 3045, 3813, 4736, 5831, 7156, 8684, 10507, 12627, 15092, 17935, 21249, 25004, 29341, 34272, 39875, 46207, 53407, 61446, 70528, 80682, 92026, 104650, 118752

Offset: 0

Vladeta Jovovic, Nov 19 2000

nonn

Number of 3 x n binary matrices with n ones up to row and column permutation.

Vladeta Jovovic, Expansion of generating function.

Cf. A002727, A049311.

a(n)= coefficient of x^n*y^n in expansion of 1 / 3!*(1 / (1 - x) / (1 - x*y)^3 / (1 - x*y^2)^3 / (1 - x*y^3) + 3 / (1 - x) / (1 - x*y) / (1 - x*y^2) / (1 - x*y^3) / (1 - x^2*y^2) / (1 - x^2*y^4) + 2 / (1 - x) / (1 - x*y^3) / (1 - x^3*y^3) / (1 - x^3*y^6)).

Empirical g.f.: -(x^8-x^7+x^6+x^4+x^2-x+1) / ((x-1)^7*(x+1)^3*(x^2-x+1)*(x^2+1)*(x^2+x+1)^3). - Colin Barker, Jul 11 2013

a(21)-a(42) from Max Alekseyev, Jan 21 2010

cp's OEIS Frontend

A002728 Number of n X (n+2) binary matrices.

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A005745 Number of n-covers of an unlabeled 3-set.

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A005746 Number of n-covers of an unlabeled 4-set.

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A353585 Square array T(n,k): row n lists the number of inequivalent matrices over Z/nZ, modulo permutations of rows and columns, of size r X c, 1 <= r <= c, c >= 1.

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A052267 Number of 2 X n matrices over GF(3) under row and column permutations.

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PARI

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A055484 Number of unlabeled 3-element intersecting families (with not necessarily distinct sets) of an n-element set.

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Programs

Mathematica

PARI

Formula

Extensions

A056204 Number of n X 5 binary matrices under row and column permutations and column complementations.

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References

Links

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Formula

A056205 Number of n X 6 binary matrices under row and column permutations and column complementations.