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.

A301757 Positive determinant values assumed by performing all permutations of entries in the 3 X 3 matrix of A301372.

Original entry on oeis.org

27, 147, 168, 171, 197, 293, 317, 331, 332, 408, 441, 469, 532, 547, 568, 643, 717, 819, 845, 901, 909, 971, 1017, 1028, 1080, 1104, 1182, 1201, 1297, 1388, 1392, 1400, 1423, 1591, 1606, 1624, 1633, 1640, 1846, 1891, 2038, 2042, 2089, 2114, 2275, 2278, 2288, 2369, 2384
Offset: 1

Views

Author

Hugo Pfoertner, Mar 26 2018

Keywords

Comments

A 3 X 3 matrix with given 9 matrix entries can produce A088021(3)=10080 distinct determinants if all positional permutations are performed. The current sequence provides the 5040 positive determinants of a conjectured optimal matrix minimizing its greatest matrix entry.

Examples

			a(1) = 27 because the smallest determinant that can be achieved from the matrix entries of A301372 is
det (( 0  1 89)
     (87 99 97)
     (54 61 20)) = 27,
.
a(5040) = 1039208:
det ((99 54  1)
     (20 97 87)
     (61  0 89)) = 1039208.
		

Crossrefs

A098072 An example of a 3 X 3 matrix with nonnegative elements that produces the maximum possible number of 10080 different determinants if all 9! permutations of the matrix elements are performed. The target is to find a matrix for which the largest element becomes as small as possible.

Original entry on oeis.org

0, 1, 17, 43, 82, 87, 88, 91, 100
Offset: 1

Views

Author

Hugo Pfoertner, Nov 19 2004

Keywords

Comments

In November 2004 this is the example with the smallest known largest element. It was found in a random search after 3 CPU (1.5 GHz Intel Itanium 2) months. No improvement was found in another 6 months of CPU time.

Crossrefs

Cf. A088021 maximal number of different determinants of an n X n matrix, A099834 different determinants of matrix with nonnegative entries <=n.
Improved solution: A301372.
Optimal solution found by exhaustive search: A316601.

Programs

  • Fortran
    ! See Links section.

A316601 Optimal solution for the problem stated in A098072.

Original entry on oeis.org

0, 3, 19, 65, 75, 83, 88, 93, 94
Offset: 1

Views

Author

Hugo Pfoertner, Jul 13 2018

Keywords

Comments

The nonexistence of solutions with maximum matrix element < 94 was proved by exhaustive search.

Crossrefs

A316602 Positive determinant values assumed by performing all permutations of entries in the 3 X 3 matrix of A316601.

Original entry on oeis.org

1, 9, 29, 67, 162, 267, 309, 430, 452, 520, 570, 712, 716, 825, 841, 844, 941, 943, 980, 1120, 1287, 1289, 1396, 1478, 1516, 1521, 1580, 1592, 1605, 1700, 1753, 1870, 1875, 1914, 1950, 1989, 2157, 2245, 2254, 2265
Offset: 1

Views

Author

Hugo Pfoertner, Jul 17 2018

Keywords

Examples

			a(1) = 1 because the smallest determinant that can be achieved from the matrix entries of A316601 is
det (( 0  3 19)
     (94 88 93)
     (83 75 65)) = 1,
.
a(5040) = 1039208:
det ((88  3 83)
     (75 94 19)
     ( 0 65 93)) = 1044316.
		

Crossrefs

Showing 1-4 of 4 results.