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 1-5 of 5 results.

A374386 a(n) is the minimal determinant of an n X n symmetric Toeplitz matrix having 0 on the main diagonal and all the first n-1 primes off-diagonal.

Original entry on oeis.org

1, 0, -4, 24, -324, -15164, -1453072, -161765904, -37905894000, -1376219654680, -718058901423168, -163742479201610036
Offset: 0

Views

Author

Stefano Spezia, Jul 07 2024

Keywords

Examples

			a(5) = -15164:
  [0, 2, 7, 3, 5]
  [2, 0, 2, 7, 3]
  [7, 2, 0, 2, 7]
  [3, 7, 2, 0, 2]
  [5, 3, 7, 2, 0]
		

Crossrefs

Cf. A374387 (maximal), A374388 (maximal absolute value), A374389 (minimal nonzero absolute value).
Cf. A374068 (minimal permanent), A374390 (maximal permanent).

Programs

  • Mathematica
    a[n_]:=Min[Table[Det[ToeplitzMatrix[Join[{0},Part[Permutations[Prime[Range[n-1]]],i]]]],{i,(n-1)!}]]; Join[{1},Array[a,10]]

Extensions

a(11) from Giorgos Kalogeropoulos, Jul 10 2024

A374387 a(n) is the maximal determinant of an n X n symmetric Toeplitz matrix having 0 on the main diagonal and all the first n-1 primes off-diagonal.

Original entry on oeis.org

1, 0, -4, 36, 129, 3340, 2287607, 162104000, 16943055268, 4059346088384, 474967482901952, 221630954408019520
Offset: 0

Views

Author

Stefano Spezia, Jul 07 2024

Keywords

Examples

			a(5) = 3340:
  [0, 5, 7, 3, 2]
  [5, 0, 5, 7, 3]
  [7, 5, 0, 5, 7]
  [3, 7, 5, 0, 5]
  [2, 3, 7, 5, 0]
		

Crossrefs

Cf. A374386 (minimal), A374388 (maximal absolute value), A374389 (minimal nonzero absolute value).
Cf. A374068 (minimal permanent), A374390 (maximal permanent).

Programs

  • Mathematica
    a[n_]:=Max[Table[Det[ToeplitzMatrix[Join[{0},Part[Permutations[Prime[Range[n-1]]],i]]]],{i,(n-1)!}]]; Join[{1},Array[a,10]]

Extensions

a(11) from Giorgos Kalogeropoulos, Jul 10 2024

A374389 a(n) is the minimal absolute value of the determinant of a nonsingular n X n symmetric Toeplitz matrix having 0 on the main diagonal and all the first n-1 primes off-diagonal.

Original entry on oeis.org

4, 24, 116, 192, 1079, 664, 720, 216
Offset: 2

Views

Author

Stefano Spezia, Jul 07 2024

Keywords

Comments

The offset is 2 because for n = 1 the unique symmetric Toeplitz matrix is singular.

Examples

			a(5) = 192:
  [0, 5, 3, 2, 7]
  [5, 0, 5, 3, 2]
  [3, 5, 0, 5, 3]
  [2, 3, 5, 0, 5]
  [7, 2, 3, 5, 0]
		

Crossrefs

Cf. A374386 (minimal), A374387 (maximal), A374388 (maximal absolute value).
Cf. A374068 (minimal permanent), A374390 (maximal permanent).

Programs

  • Mathematica
    a[n_]:=Min[Select[Table[Abs[Det[ToeplitzMatrix[Join[{0},Part[Permutations[Prime[Range[n-1]]],i]]]]],{i,(n-1)!}],Positive]]; Array[a,8,2]

A374390 a(n) is the maximal permanent of an n X n symmetric Toeplitz matrix having 0 on the main diagonal and all the first n-1 primes off-diagonal.

Original entry on oeis.org

1, 0, 4, 36, 1936, 144260, 31972988, 6800311204, 2560967581304, 975834087080060, 557171087172087364
Offset: 0

Views

Author

Stefano Spezia, Jul 07 2024

Keywords

Examples

			a(5) = 144260:
  [0, 7, 5, 3, 2]
  [7, 0, 7, 5, 3]
  [5, 7, 0, 7, 5]
  [3, 5, 7, 0, 7]
  [2, 3, 5, 7, 0]
		

Crossrefs

Cf. A374345.
Cf. A374068 (minimal permanent).

Programs

  • Mathematica
    a[n_]:=Max[Table[Permanent[ToeplitzMatrix[Join[{0},Part[Permutations[Prime[Range[n-1]]],i]]]],{i,(n-1)!}]]; Join[{1},Array[a,10]]

A374620 a(n) is the number of distinct values of the determinant of an n X n symmetric Toeplitz matrix having 0 on the main diagonal and all the first n-1 primes off-diagonal.

Original entry on oeis.org

1, 1, 1, 2, 6, 24, 120, 717, 5040, 40314, 362874
Offset: 0

Views

Author

Stefano Spezia, Jul 14 2024

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_]:=CountDistinct[Table[Det[ToeplitzMatrix[Join[{0},Part[Permutations[Prime[Range[n-1]]], i]]]], {i, (n -1)!}]]; Join[{1}, Array[a, 10]]

Formula

a(n) <= (n-1)! for n > 0.
Showing 1-5 of 5 results.