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 1-3 of 3 results.

A296351 List of nonzero determinants of Bordered Lights Out matrices BL_k.

Original entry on oeis.org

-3, -7, 2197, -34391, -4002939, 276762749, -133968364171875, -239121867667810023, 105499562776343659717577, -3916466797684156666150912, -684705401333128471131344184438251, 225821697750350580274314863789803277056101, -2768960885387220187221550050659464666284508951
Offset: 1

Views

Author

N. J. A. Sloane, Dec 14 2017

Keywords

Comments

For the orders of these matrices see A296350.

Crossrefs

Programs

  • Mathematica
    J[n_] := Table[If[Abs[i - j] < 2, 1, 0], {i, 1, n}, {j, 1, n}]; BL[n_] := KroneckerProduct[(jn = J[n]), (in = IdentityMatrix[n])] + KroneckerProduct[in, jn] - IdentityMatrix[n^2]; Select[Table[Det @ BL[n], {n, 2, 21}], # != 0 &] (* Amiram Eldar, May 13 2020 *)

A296353 List of nonzero determinants of Unbordered Lights Out matrices UBL_k.

Original entry on oeis.org

80, -1215, 142805, -7004233215, 870763219280, 87789257318405, 45421053339522658203125, -7059547871395329316834815, -19913109703689000789427796194815, 42950557989828549673287680, 940419421873808776346210289268985127605
Offset: 1

Views

Author

N. J. A. Sloane, Dec 14 2017

Keywords

Comments

For the orders of these matrices see A296352.

Crossrefs

Programs

  • Mathematica
    K[n_] := Table[If[MemberQ[{0, 1, n - 1}, Abs[i - j]], 1, 0], {i, 1, n}, {j, 1, n}]; UL[n_] := KroneckerProduct[(kn = K[n]), (in = IdentityMatrix[n])] + KroneckerProduct[in, kn] - IdentityMatrix[n^2]; Select[Table[Det @ UL[n], {n, 3, 20}], # != 0 &] (* Amiram Eldar, May 13 2020 *)

A296350 List of numbers k such that the determinant of the Bordered Lights Out matrix BL_k is nonzero.

Original entry on oeis.org

2, 3, 6, 7, 8, 10, 12, 13, 15, 16, 18, 20, 21, 22, 25, 26, 27, 28, 30, 31, 32, 33, 36, 37, 38, 40, 42, 43, 45, 46, 48, 50, 51, 52, 55, 56, 57, 58, 60, 61, 62, 63, 66, 67, 68, 70, 72, 73, 75, 76, 78, 80, 81, 82, 85, 86, 87, 88, 90, 91, 92, 93, 96, 97, 98, 100, 102
Offset: 1

Views

Author

N. J. A. Sloane, Dec 14 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[2, 102], Mod[# + 1, 5] > 0 && Mod[# + 1, 6] > 0 &] (* Amiram Eldar, May 13 2020 *)

Formula

Numbers m > 1 such that m+1 is not divisible by 5 nor by 6. - Amiram Eldar, May 13 2020

Extensions

More terms from Amiram Eldar, May 13 2020
Showing 1-3 of 3 results.