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.

A217637 T(n,k)=Number of nXk arrays of the minimum value of corresponding elements and their horizontal and vertical neighbors in a random 0..1 nXk array.

Original entry on oeis.org

2, 2, 2, 4, 6, 4, 6, 16, 16, 6, 10, 38, 66, 38, 10, 16, 98, 244, 244, 98, 16, 26, 244, 968, 1418, 968, 244, 26, 42, 614, 3726, 8706, 8706, 3726, 614, 42, 68, 1542, 14520, 52120, 83074, 52120, 14520, 1542, 68, 110, 3872, 56352, 315378, 773348, 773348, 315378
Offset: 1

Views

Author

R. H. Hardin, Oct 09 2012

Keywords

Comments

Number of maximal independent sets in the graph P_2 X P_n X P_k. - Andrew Howroyd, Jun 10 2017

Examples

			Table starts
...2.....2........4..........6...........10..............16................26
...2.....6.......16.........38...........98.............244...............614
...4....16.......66........244..........968............3726.............14520
...6....38......244.......1418.........8706...........52120............315378
..10....98......968.......8706........83074..........773348...........7272142
..16...244.....3726......52120.......773348........11181454.........163361868
..26...614....14520.....315378......7272142.......163361868........3709621842
..42..1542....56352....1900838.....68138974......2378097084.......83923710538
..68..3872...218978...11472148....639248556.....34661572702.....1901055652804
.110..9726...850620...69210290...5994907930....505010822224....43046530809006
.178.24426..3304624..417586442..56226693158...7358779655656...974841850791586
.288.61348.12837742.2519466108.527340415924.107224919634686.22075731493018104
...
Some solutions for n=3 k=4
..1..0..0..1....0..0..0..1....1..0..1..1....1..1..0..0....1..0..0..0
..0..0..0..0....0..0..1..1....0..0..0..1....0..0..1..0....1..1..0..0
..1..0..0..0....0..0..0..1....1..0..1..1....0..0..0..1....1..0..0..0
		

Crossrefs

Columns 1-3 are A006355(n+1), A217631, A217632.
Cf. A197054.

A217631 Number of nX2 arrays of the minimum value of corresponding elements and their horizontal and vertical neighbors in a random 0..1 nX2 array.

Original entry on oeis.org

0, 2, 6, 16, 38, 98, 244, 614, 1542, 3872, 9726, 24426, 61348, 154078, 386974, 971904, 2440982, 6130642, 15397396, 38671286, 97124758, 243933408, 612650254, 1538699994, 3864517572, 9705918062, 24376870766, 61223660096, 153766108518
Offset: 0

Views

Author

R. H. Hardin Oct 09 2012

Keywords

Comments

Also, number of maximal independent sets in the 3-dimensional (2, 2, n) grid graph. [Euler et al.] - N. J. A. Sloane, Nov 21 2013
Column 2 of A217637.

Examples

			Some solutions for n=3
..0..0....0..0....0..0....1..1....0..0....1..0....1..0....0..1....1..1....0..0
..0..1....0..0....0..1....0..1....1..0....0..0....0..0....0..0....1..1....1..0
..0..0....1..0....1..1....0..0....0..0....0..0....1..0....0..1....1..1....1..1
		

Crossrefs

Formula

G.f. = (2*x+4*x^2+4*x^3)/(1-x-3*x^2-2*x^3). [Euler et al.] - N. J. A. Sloane, Nov 21 2013
Empirical: a(n) = a(n-1) + 3*a(n-2) + 2*a(n-3). (Follows from g.f. - N. J. A. Sloane, Nov 21 2013)

A231884 Number of maximal 2-independent sets in the 3-dimensional (2, 2, n) grid graph.

Original entry on oeis.org

0, 4, 4, 20, 32, 80, 180, 408, 940, 2072, 4824, 10792, 24660, 55748, 126760, 287584, 652280, 1481184, 3359900, 7627296, 17305472, 39277688, 89131928, 202276640, 459045772, 1041743020, 2364140452, 5365103100, 12175556108, 27630957644, 62705400664, 142302685268
Offset: 0

Views

Author

N. J. A. Sloane, Nov 17 2013

Keywords

Crossrefs

Programs

  • Mathematica
    Join[{0}, LinearRecurrence[{0, 3, 4, 4, 0, -9, -3}, {4, 4, 20, 32, 80, 180, 408}, 31]] (* Jean-François Alcover, Nov 01 2017 *)
  • PARI
    concat(0, Vec(4*x*(1 + x)*(1 + 2*x^2 - x^3 - 2*x^4 - x^5) / (1 - 3*x^2 - 4*x^3 - 4*x^4 + 9*x^6 + 3*x^7) + O(x^40))) \\ Colin Barker, Oct 04 2017

Formula

Euler et al. give an explicit g.f. and recurrence.
From Colin Barker, Oct 04 2017: (Start)
G.f.: 4*x*(1 + x)*(1 + 2*x^2 - x^3 - 2*x^4 - x^5) / (1 - 3*x^2 - 4*x^3 - 4*x^4 + 9*x^6 + 3*x^7).
a(n) = 3*a(n-2) + 4*a(n-3) + 4*a(n-4) - 9*a(n-6) - 3*a(n-7) for n>7.
(End)

Extensions

Terms a(11) and beyond from Andrew Howroyd, Jun 10 2017

A231887 Number of maximal 2-independent sets in the 3-dimensional (3, 3, n) grid graph.

Original entry on oeis.org

0, 11, 46, 182, 1026, 4836, 23922, 118674, 584516, 2889306, 14266546, 70455052, 347980122, 1718525298, 8487343508, 41916544250, 207013446378, 1022380190332, 5049238367202, 24936725579450, 123155267567884, 608228181611074, 3003862808227186, 14835208208589988
Offset: 0

Views

Author

N. J. A. Sloane, Nov 17 2013

Keywords

Crossrefs

Extensions

Terms a(13) and beyond from Andrew Howroyd, Jun 10 2017

A231888 Number of maximal 3-independent sets in the 3-dimensional (3, 3, n) grid graph.

Original entry on oeis.org

0, 7, 26, 57, 190, 646, 1914, 5960, 18824, 58248, 181196, 565328, 1759720, 5477376, 17062956, 53131824, 165443096, 515219344, 1604410136, 4996129756, 15558217340, 48448930636, 150871392396, 469819443204, 1463035474136, 4555944690588, 14187380873768
Offset: 0

Views

Author

N. J. A. Sloane, Nov 17 2013

Keywords

Crossrefs

Extensions

Terms a(13) and beyond from Andrew Howroyd, Jun 10 2017
Showing 1-5 of 5 results.