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 1-4 of 4 results.

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]
		

Crossrefs

Rows n=0..3 are A000012, A000670, A331644, A331645.
Columns k=0..3 are A000012, A032020, A331646, A331647.

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).

A331644 Number of nonnegative integer matrices with n columns and any number of distinct nonzero rows with column sums 2.

Original entry on oeis.org

1, 1, 13, 313, 14797, 1095601, 119621653, 17943752233, 3550217905597, 894951415465441, 280109128908963493, 106563994919500072153, 48431841090878234155597, 25916389944261925021739281, 16128299505539619187866596533, 11549663940282035980807700520073
Offset: 0

Views

Author

Andrew Howroyd, Jan 23 2020

Keywords

Examples

			The a(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]
		

Crossrefs

Row n=2 of A331568.
Cf. A331645.

A331705 Number of nonnegative integer matrices with n distinct columns and any number of distinct nonzero rows with column sums 3 and columns in decreasing lexicographic order.

Original entry on oeis.org

1, 3, 42, 1900, 184550, 29724388, 7137090958, 2393644524156, 1068870144819960, 613045196870306340, 439190550399403297437, 384354189217232125992320, 403475262029493557613389128, 500401167055816780694578266750, 723870101627745660876118985228250
Offset: 0

Views

Author

Andrew Howroyd, Jan 25 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.

Examples

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

Crossrefs

Row n=3 of A331570.

Formula

a(n) = (1/n!)*Sum_{k=0..n} abs(Stirling1(n, k)) * A331645(k).

A331710 Number of nonnegative integer matrices with n columns and any number of distinct nonzero rows with column sums 3 and columns in nonincreasing lexicographic order.

Original entry on oeis.org

1, 3, 45, 1987, 190379, 30474159, 7287577611, 2436916655479, 1085776582252197, 621663581843731535, 444746638465623906738, 388773810523972862494769, 407727415097448880517583006, 505268334502886263575349570013, 730406898110019766652845079212010
Offset: 0

Views

Author

Andrew Howroyd, Jan 25 2020

Keywords

Comments

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

Examples

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

Crossrefs

Row n=3 of A331572.

Formula

a(n) = (1/n!)*Sum_{k=0..n} abs(Stirling1(n, k)) * A331645(k).
Showing 1-4 of 4 results.