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 1-8 of 8 results.

A330942 Array read by antidiagonals: A(n,k) is the number of binary matrices with k columns and any number of nonzero rows with n ones in every column and columns in nonincreasing lexicographic order.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 4, 7, 1, 1, 1, 8, 75, 32, 1, 1, 1, 16, 1105, 2712, 161, 1, 1, 1, 32, 20821, 449102, 116681, 842, 1, 1, 1, 64, 478439, 122886128, 231522891, 5366384, 4495, 1, 1, 1, 128, 12977815, 50225389432, 975712562347, 131163390878, 256461703, 24320, 1, 1
Offset: 0

Views

Author

Andrew Howroyd, Jan 13 2020

Keywords

Comments

The condition that the columns be in nonincreasing order is equivalent to considering nonequivalent matrices up to permutation of columns.
A(n,k) is the number of labeled n-uniform hypergraphs with multiple edges allowed and with k edges and no isolated vertices. When n=2 these objects are multigraphs.

Examples

			Array begins:
============================================================
n\k | 0 1    2         3              4                5
----+-------------------------------------------------------
  0 | 1 1    1         1              1                1 ...
  1 | 1 1    2         4              8               16 ...
  2 | 1 1    7        75           1105            20821 ...
  3 | 1 1   32      2712         449102        122886128 ...
  4 | 1 1  161    116681      231522891     975712562347 ...
  5 | 1 1  842   5366384   131163390878 8756434117294432 ...
  6 | 1 1 4495 256461703 78650129124911 ...
  ...
The A(2,2) = 7 matrices are:
   [1 0]  [1 0]  [1 0]  [1 1]  [1 0]  [1 0]  [1 1]
   [1 0]  [0 1]  [0 1]  [1 0]  [1 1]  [0 1]  [1 1]
   [0 1]  [1 0]  [0 1]  [0 1]  [0 1]  [1 1]
   [0 1]  [0 1]  [1 0]

Links

Crossrefs

Rows n=1..3 are A000012, A121316, A136246.
Columns k=0..3 are A000012, A000012, A226994, A137220.
The version with nonnegative integer entries is A331315.
Other variations considering distinct rows and columns and equivalence under different combinations of permutations of rows and columns are:
All solutions: A262809 (all), A331567 (distinct rows).
Up to row permutation: A188392, A188445, A331126, A331039.
Up to column permutation: this sequence, A331571, A331277, A331569.
Nonisomorphic: A331461, A331510, A331508, A331509.
Cf. A331638.

Programs

  • Mathematica
    T[n_, k_] := With[{m = n k}, Sum[Binomial[Binomial[j, n] + k - 1, k] Sum[ (-1)^(i - j) Binomial[i, j], {i, j, m}], {j, 0, m}]];
Table[T[n - k, k], {n, 0, 9}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Apr 10 2020, from PARI *)
  • PARI
    T(n, k)={my(m=n*k); sum(j=0, m, binomial(binomial(j, n)+k-1, k)*sum(i=j, m, (-1)^(i-j)*binomial(i, j)))}

Formula

A(n,k) = Sum_{j=0..n*k} binomial(binomial(j,n)+k-1, k) * (Sum_{i=j..n*k} (-1)^(i-j)*binomial(i,j)).
A(n, k) = Sum_{j=0..k} abs(Stirling1(k, j))*A262809(n, j)/k!.
A(n, k) = Sum_{j=0..k} binomial(k-1, k-j)*A331277(n, j).
A331638(n) = Sum_{d|n} A(n/d, d).

A331571 Array read by antidiagonals: A(n,k) is the number of binary matrices with k columns and any number of distinct nonzero rows with n ones in every column and columns in nonincreasing lexicographic order.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 0, 1, 1, 4, 3, 0, 1, 1, 8, 23, 0, 0, 1, 1, 16, 290, 184, 0, 0, 1, 1, 32, 4298, 17488, 840, 0, 0, 1, 1, 64, 79143, 2780752, 771305, 0, 0, 0, 1, 1, 128, 1702923, 689187720, 1496866413, 21770070, 0, 0, 0, 1, 1, 256, 42299820, 236477490418, 5261551562405, 585897733896, 328149360, 0, 0, 0, 1
Offset: 0

Views

Author

Andrew Howroyd, Jan 20 2020

Keywords

Comments

The condition that the columns be in nonincreasing order is equivalent to considering nonequivalent matrices up to permutation of columns.

Examples

			Array begins:
===============================================================
n\k | 0 1 2   3         4               5                 6
----+----------------------------------------------------------
  0 | 1 1 1   1         1               1                 1 ...
  1 | 1 1 2   4         8              16                32 ...
  2 | 1 0 3  23       290            4298             79143 ...
  3 | 1 0 0 184     17488         2780752         689187720 ...
  4 | 1 0 0 840    771305      1496866413     5261551562405 ...
  5 | 1 0 0   0  21770070    585897733896 30607728081550686 ...
  6 | 1 0 0   0 328149360 161088785679360 ...
  ...
The A(2,2) = 3 matrices are:
   [1 1]  [1 0]  [1 0]
   [1 0]  [1 1]  [0 1]
   [0 1]  [0 1]  [1 1]

Links

Crossrefs

Rows n=0..4 are A000012, A011782, A060090, A060491, A331652.
Cf. A330942, A331567, A331569, A331570, A331572, A331653.

Programs

  • PARI
    WeighT(v)={Vec(exp(x*Ser(dirmul(v, vector(#v, n, (-1)^(n-1)/n))))-1, -#v)}
D(p, n, k)={my(v=vector(n)); for(i=1, #p, v[p[i]]++); binomial(WeighT(v)[n] + k - 1, k)/prod(i=1, #v, i^v[i]*v[i]!)}
T(n, k)={ my(m=n*k+1, q=Vec(exp(intformal(O(x^m) - x^n/(1-x)))), f=Vec(serlaplace(1/(1+x) + O(x*x^m))/(x-1))); if(n==0, 1, sum(j=1, m, my(s=0); forpart(p=j, s+=(-1)^#p*D(p, n, k), [1, n]); s*sum(i=j, m, q[i-j+1]*f[i]))); }

Formula

A(n, k) = Sum_{j=0..k} abs(Stirling1(k, j))*A331567(n, j)/k!.
A(n, k) = Sum_{j=0..k} binomial(k-1, k-j)*A331569(n, j).
A(n, k) = 0 for k > 0, n > 2^(k-1).
A331653(n) = Sum_{d|n} A(n/d, d).

A331569 Array read by antidiagonals: A(n,k) is the number of binary matrices with k distinct columns and any number of distinct nonzero rows with n ones in every column and columns in decreasing lexicographic order.

Original entry on oeis.org

1, 1, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 3, 0, 1, 0, 1, 17, 0, 0, 1, 0, 1, 230, 184, 0, 0, 1, 0, 1, 3264, 16936, 840, 0, 0, 1, 0, 1, 60338, 2711904, 768785, 0, 0, 0, 1, 0, 1, 1287062, 675457000, 1493786233, 21770070, 0, 0, 0, 1, 0, 1, 31900620, 232383728378, 5254074934990, 585810653616, 328149360, 0, 0, 0, 1
Offset: 0

Views

Author

Andrew Howroyd, Jan 20 2020

Keywords

Comments

The condition that the columns be in decreasing order is equivalent to considering nonequivalent matrices with distinct columns up to permutation of columns.
A(n,k) is the number of k-block n-uniform T_0 set systems without isolated vertices.

Examples

			Array begins:
===============================================================
n\k | 0 1 2   3         4               5                 6
----+----------------------------------------------------------
  0 | 1 1 0   0         0               0                 0 ...
  1 | 1 1 1   1         1               1                 1 ...
  2 | 1 0 3  17       230            3264             60338 ...
  3 | 1 0 0 184     16936         2711904         675457000 ...
  4 | 1 0 0 840    768785      1493786233     5254074934990 ...
  5 | 1 0 0   0  21770070    585810653616 30604798810581906 ...
  6 | 1 0 0   0 328149360 161087473081920 ...
  ...
The A(2,2) = 3 matrices are:
   [1 1]  [1 0]  [1 0]
   [1 0]  [1 1]  [0 1]
   [0 1]  [0 1]  [1 1]

Links

Crossrefs

Rows n=1..4 are A000012, A331649, A094631, A331650.
Cf. A330942, A331039, A331567, A331570, A331571, A331572, A331651.

Programs

  • PARI
    WeighT(v)={Vec(exp(x*Ser(dirmul(v, vector(#v, n, (-1)^(n-1)/n))))-1, -#v)}
D(p, n, k)={my(v=vector(n)); for(i=1, #p, v[p[i]]++); binomial(WeighT(v)[n], k)/prod(i=1, #v, i^v[i]*v[i]!)}
T(n, k)={ my(m=n*k+1, q=Vec(exp(intformal(O(x^m) - x^n/(1-x)))), f=Vec(serlaplace(1/(1+x) + O(x*x^m))/(x-1))); if(n==0, k<=1, sum(j=1, m, my(s=0); forpart(p=j, s+=(-1)^#p*D(p, n, k), [1, n]); s*sum(i=j, m, q[i-j+1]*f[i]))); }

Formula

A(n, k) = Sum_{j=0..k} Stirling1(k, j)*A331567(n, j)/k!.
A(n, k) = Sum_{j=0..k} (-1)^(k-j)*binomial(k-1, k-j)*A331571(n, j).
A331651(n) = Sum_{d|n} A(n/d, d).

A331568 Array read by antidiagonals: A(n,k) is the number of nonnegative integer matrices with k columns and any number of distinct nonzero rows with column sums n.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 13, 13, 3, 1, 1, 75, 313, 87, 3, 1, 1, 541, 14797, 11655, 539, 5, 1, 1, 4683, 1095601, 4498191, 439779, 2483, 11, 1, 1, 47293, 119621653, 3611504823, 1390686419, 14699033, 14567, 13, 1, 1, 545835, 17943752233, 5192498314767, 12006713338683, 397293740555, 453027131, 81669, 19, 1
Offset: 0

Views

Author

Andrew Howroyd, Jan 21 2020

Keywords

Examples

			Array begins:
================================================================
n\k | 0  1     2         3               4                 5
----+-----------------------------------------------------------
  0 | 1  1     1         1               1                 1 ...
  1 | 1  1     3        13              75               541 ...
  2 | 1  1    13       313           14797           1095601 ...
  3 | 1  3    87     11655         4498191        3611504823 ...
  4 | 1  3   539    439779      1390686419    12006713338683 ...
  5 | 1  5  2483  14699033    397293740555 37366422896708825 ...
  6 | 1 11 14567 453027131 105326151279287 ...
  ...
The A(2,2) = 13 matrices are:
   [1 1]  [1 1]  [1 0]  [1 0]  [0 1]  [0 1]
   [1 0]  [0 1]  [1 1]  [0 1]  [1 1]  [1 0]
   [0 1]  [1 0]  [0 1]  [1 1]  [1 0]  [1 1]
.
   [2 1]  [2 0]  [1 2]  [1 0]  [0 2]  [0 1]  [2 2]
   [0 1]  [0 2]  [1 0]  [1 2]  [2 0]  [2 1]

Links

Crossrefs

Rows n=0..3 are A000012, A000670, A331644, A331645.
Columns k=0..3 are A000012, A032020, A331646, A331647.
Cf. A219585, A331315, A331567, A331570, A331572, A331648.

Programs

  • PARI
    EulerT(v)={Vec(exp(x*Ser(dirmul(v, vector(#v, n, 1/n))))-1, -#v)}
D(p, n, k)={my(v=vector(n)); for(i=1, #p, v[p[i]]++); EulerT(v)[n]^k/prod(i=1, #v, i^v[i]*v[i]!)}
T(n, k)={ my(m=n*k+1, q=Vec(exp(intformal(O(x^m) - x^n/(1-x)))), f=Vec(serlaplace(1/(1+x) + O(x*x^m))/(x-1))); if(n==0, 1, sum(j=1, m, my(s=0); forpart(p=j, s+=(-1)^#p*D(p, n, k), [1, n]); s*sum(i=j, m, q[i-j+1]*f[i]))); }

Formula

A331648(n) = Sum_{d|n} A(n/d, d).

A331640 Number of binary matrices with n columns and any number of distinct nonzero rows with 2 ones in every column.

Original entry on oeis.org

1, 0, 6, 120, 6174, 449520, 49686726, 7455901320, 1479839874414, 373573957133280, 117097298726892246, 44596327028174342520, 20287402287658565190654, 10864410524883717498300240, 6765647366010527963979060966, 4847736403559133115838948559720
Offset: 0

Views

Author

Andrew Howroyd, Jan 23 2020

Keywords

Examples

			The a(2) = 6 matrices are:
   [1 1]  [1 1]  [1 0]  [1 0]  [0 1]  [0 1]
   [1 0]  [0 1]  [1 1]  [0 1]  [1 1]  [1 0]
   [0 1]  [1 0]  [0 1]  [1 1]  [1 0]  [1 1]

Links

Crossrefs

Row n=2 of A331567.
Cf. A331641.

A331641 Number of binary matrices with n columns and any number of distinct nonzero rows with 3 ones in every column.

Original entry on oeis.org

1, 0, 0, 1104, 413088, 329520720, 491236986720, 1181472603447024, 4293813878010363168, 22458802092186671702160, 162578056150830848930694240, 1578225306620809383358117044144, 20018143307386606584084592083087648, 324613983359213454501611571669979410000
Offset: 0

Views

Author

Andrew Howroyd, Jan 23 2020

Keywords

Links

Crossrefs

Row n=3 of A331567.
Cf. A331640.

A331642 Number of binary matrices with 5 columns and any number of distinct nonzero rows with n ones in every column.

Original entry on oeis.org

1, 541, 449520, 329520720, 179438982360, 70302503250720, 19330575525676800, 3970208270468160000, 607903979228432409600, 70957474321212775296000, 6333776843022254545920000, 419451089306915623845888000, 20409207470176316989317120000, 721332390787558700622151680000
Offset: 0

Views

Author

Andrew Howroyd, Jan 23 2020

Keywords

Comments

The final term a(16) = 31! corresponds to the number of ways to order the 31 possible nonzero rows.

Links

Crossrefs

Column k=5 of A331567.
Cf. A331127.

A331643 Number of binary matrices with distinct nonzero rows, a total of n ones and each column with the same number of ones.

Original entry on oeis.org

1, 3, 13, 81, 541, 4803, 47293, 552009, 7088365, 102697083, 1622632573, 28141672449, 526858348381, 10648798871763, 230283520498573, 5317134540336849, 130370767029135901, 3385908728450965323, 92801587319328411133, 2677804893723072559401, 81124826179976677328845
Offset: 1

Views

Author

Andrew Howroyd, Jan 24 2020

Keywords

Examples

			The a(2) = 3 matrices are:
  [1 0]  [0 1]  [1 1]
  [0 1]  [1 0]

Crossrefs

Cf. A331567.

Formula

a(n) = Sum_{d|n} A331567(n/d, d).
Showing 1-8 of 8 results.

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