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.

A350938 Maximal permanent of an n X n Toeplitz matrix using the integers 1 to 2*n - 1.

Original entry on oeis.org

1, 1, 11, 296, 14502, 1153889, 134713213, 21788125930
Offset: 0

Views

Author

Stefano Spezia, Jan 26 2022

Keywords

Comments

Also maximal permanent of an n X n Hankel matrix using the integers 1 to 2*n - 1. - Stefano Spezia, Dec 22 2023

Examples

			a(2) = 11:
    3    1
    2    3
a(3) = 296:
    5    3    2
    4    5    3
    1    4    5
		

Crossrefs

Cf. A322908, A323254, A350931, A350937 (minimal).

Programs

  • Python
    from itertools import permutations
    from sympy import Matrix
    def A350938(n): return 1 if n == 0 else max(Matrix([p[n-1-i:2*n-1-i] for i in range(n)]).per() for p in permutations(range(1,2*n))) # Chai Wah Wu, Jan 27 2022

Extensions

a(5) from Alois P. Heinz, Jan 26 2022
a(6) from Lucas A. Brown, Sep 04 2022
a(7) from Giovanni Resta, Oct 13 2022

A351019 Minimal permanent of an n X n symmetric Toeplitz matrix using the integers 1 to n.

Original entry on oeis.org

1, 1, 5, 36, 480, 9991, 296913, 12099604, 637590728, 43090005714, 3550491371994, 359557627057876
Offset: 0

Views

Author

Stefano Spezia, Jan 29 2022

Keywords

Examples

			a(3) = 36:
    2    1    3
    1    2    1
    3    1    2
a(4) = 480:
    2    1    3    4
    1    2    1    3
    3    1    2    1
    4    3    1    2
a(5) = 9991:
    3    1    2    4    5
    1    3    1    2    4
    2    1    3    1    2
    4    2    1    3    1
    5    4    2    1    3
		

Crossrefs

Cf. A204235, A307783, A350937, A351020 (maximal).

Programs

  • Python
    from itertools import permutations
    from sympy import Matrix
    def A351019(n): return 1 if n == 0 else min(Matrix([p[i:0:-1]+p[0:n-i] for i in range(n)]).per() for p in permutations(range(1,n+1))) # Chai Wah Wu, Jan 31 2022

Extensions

a(9) from Alois P. Heinz, Jan 31 2022
a(10)-a(11) from Lucas A. Brown, Sep 06 2022

A358569 a(n) is the minimal permanent of an n X n Toeplitz matrix using the integers 0 to 2*(n - 1).

Original entry on oeis.org

1, 0, 1, 16, 451, 17376, 1022546
Offset: 0

Views

Author

Stefano Spezia, Nov 22 2022

Keywords

Comments

Also minimal permanent of an n X n Hankel matrix using the integers 0 to 2*(n - 1). - Stefano Spezia, Dec 22 2023

Examples

			a(2) = 1:
    [1, 0;
     2, 1]
a(3) = 16:
    [0, 1, 3;
     2, 0, 1;
     4, 2, 0]
		

Crossrefs

Cf. A350937 (integers from 1 to 2*n - 1), A358567 (minimal determinant), A358568 (maximal determinant), A358570 (maximal).

Extensions

a(5)-a(6) from Lucas A. Brown, Dec 03 2022

A350939 Minimal permanent of an n X n Toeplitz matrix using the first 2*n - 1 prime numbers.

Original entry on oeis.org

1, 2, 19, 496, 29609, 3009106, 498206489
Offset: 0

Views

Author

Stefano Spezia, Jan 26 2022

Keywords

Comments

For n X n Hankel matrices the same minimal permanents appear.

Examples

			a(2) = 19:
    2    3
    5    2
a(3) = 496:
    2    3    7
    5    2    3
   11    5    2
		

Crossrefs

Programs

  • Mathematica
    a[n_] := Min[Table[Permanent[HankelMatrix[Join[Drop[per = Part[Permutations[Prime[Range[2 n - 1]]], i], n], {Part[per, n]}], Join[{Part[per, n]}, Drop[per, - n]]]], {i, (2 n - 1) !}]]; Join[{1}, Array[a, 5]] (* Stefano Spezia, Feb 06 2024 *)
  • PARI
    a(n) = my(v=[1..2*n-1], m=+oo, d); forperm(v, p, d = matpermanent(matrix(n, n, i, j, prime(p[i+j-1]))); if (dMichel Marcus, Feb 08 2024
  • Python
    from itertools import permutations
    from sympy import Matrix, prime
    def A350939(n): return 1 if n == 0 else min(Matrix([p[n-1-i:2*n-1-i] for i in range(n)]).per() for p in permutations(prime(i) for i in range(1,2*n))) # Chai Wah Wu, Jan 27 2022
    

Extensions

a(5) from Alois P. Heinz, Jan 26 2022
a(6) from Lucas A. Brown, Sep 05 2022

A368351 a(n) is the minimal determinant of an n X n Hankel matrix using the integers 1 to 2*n - 1.

Original entry on oeis.org

1, 1, -7, -105, -1810, -48098, -3051554, -175457984
Offset: 0

Views

Author

Stefano Spezia, Dec 22 2023

Keywords

Examples

			a(2) = -7:
  2, 3;
  3, 1.
a(3) = -105:
  2, 4, 5;
  4, 5, 1;
  5, 1, 3.
a(4) = -1810:
  4, 3, 7, 1;
  3, 7, 1, 2;
  7, 1, 2, 5;
  1, 2, 5, 6.
		

Crossrefs

Cf. A350931 (maximal absolute value), A368352 (maximal).
Cf. A350937 (minimal permanent), A350938 (maximal permanent).

Extensions

a(6)-a(7) from Lucas A. Brown, Aug 26 2024

A368352 a(n) is the maximal determinant of an n X n Hankel matrix using the integers 1 to 2*n - 1.

Original entry on oeis.org

1, 1, 5, 42, 2294, 71753, 2737409, 114381074
Offset: 0

Views

Author

Stefano Spezia, Dec 22 2023

Keywords

Examples

			a(2) = 5:
  3, 1;
  1, 2.
a(3) = 42:
  2, 5, 3;
  5, 3, 4;
  3, 4, 1.
a(4) = 2294:
  2, 3, 6, 7;
  3, 6, 7, 1;
  6, 7, 1, 5;
  7, 1, 5, 4.
		

Crossrefs

Cf. A350931 (maximal absolute value), A368351 (minimal).
Cf. A350937 (minimal permanent), A350938 (maximal permanent).

Extensions

a(6)-a(7) from Lucas A. Brown, Aug 26 2024

A351610 Minimal permanent of an n X n symmetric matrix using the integers 1 to n*(n + 1)/2.

Original entry on oeis.org

1, 1, 7, 163, 9850, 1243806, 284995981
Offset: 0

Views

Author

Stefano Spezia, Feb 14 2022

Keywords

Examples

			a(3) = 163:
   1    2    3
   2    5    4
   3    4    6
a(4) = 9850:
   1    2    3    4
   2    8    5    6
   3    5    9    7
   4    6    7   10
		

Crossrefs

Extensions

a(5)-a(6) from Hugo Pfoertner, Feb 15 2022

A369943 a(n) is the number of distinct values of the permanent of an n X n Hankel matrix using the integers 1 to 2*n - 1.

Original entry on oeis.org

1, 1, 2, 49, 2117, 156189, 16943487
Offset: 0

Views

Author

Stefano Spezia, Feb 06 2024

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := CountDistinct[Table[Permanent[HankelMatrix[Join[Drop[per = Part[Permutations[Range[2 n - 1]], i], n],{Part[per, n]}], Join[{Part[per, n]}, Drop[per, - n]]]], {i, (2 n - 1) !}]]; Join[{1}, Array[a, 5]]
  • PARI
    a(n) = my(v=[1..2*n-1], list=List()); forperm(v, p, listput(list, matpermanent(matrix(n, n, i, j, p[i+j-1])));); #Set(list); \\ Michel Marcus, Feb 08 2024
    
  • Python
    from itertools import permutations
    from sympy import Matrix
    def A369943(n): return len({Matrix([p[i:i+n] for i in range(n)]).per() for p in permutations(range(1,n<<1))}) # Chai Wah Wu, Feb 12 2024

Extensions

a(6) from Michel Marcus, Feb 08 2024
Showing 1-8 of 8 results.