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.

A218354 T(n,k) = Hilltop maps: number of nXk binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or vertical neighbor in a random 0..1 n X k array.

Original entry on oeis.org

1, 3, 3, 5, 11, 5, 9, 41, 41, 9, 17, 149, 291, 149, 17, 31, 547, 2069, 2069, 547, 31, 57, 2007, 14811, 28661, 14811, 2007, 57, 105, 7361, 105913, 401253, 401253, 105913, 7361, 105, 193, 27001, 757305, 5609569, 10982565, 5609569, 757305, 27001, 193, 355
Offset: 1

Views

Author

R. H. Hardin, Oct 26 2012

Keywords

Comments

From Andrew Howroyd, May 10 2017: (Start)
Number of n X k binary matrices with every 1 vertically or horizontally adjacent to some 0.
Number of dominating sets in the grid graph P_n X P_k. (End)

Examples

			Table starts
....1.......3...........5..............9.................17
....3......11..........41............149................547
....5......41.........291...........2069..............14811
....9.....149........2069..........28661.............401253
...17.....547.......14811.........401253...........10982565
...31....2007......105913........5609569..........300126903
...57....7361......757305.......78394141.........8199377227
..105...27001.....5415209.....1095695529.......224032447213
..193...99043....38722037....15314367301......6121258910011
..355..363299...276885777...214044940145....167250519310183
..653.1332617..1979899795..2991651891557...4569773233045519
.1201.4888173.14157473937.41813576818545.124859601874166153
...
Some solutions for n=3 k=4
..1..0..1..1....1..1..1..0....1..1..1..0....1..0..1..1....1..0..1..1
..1..0..1..0....1..0..1..0....0..0..1..0....1..0..1..1....1..1..0..1
..0..0..1..0....1..1..0..1....0..1..1..1....1..1..1..1....1..1..1..0
		

Crossrefs

Columns 1-7 are A000213(n+1), A218348, A218349, A218350, A218351, A218352, A218353.
Diagonal is A133515.
Cf. A089934 (independent vertex sets), A210662 (matchings).

Formula

Empirical for column k:
k=1: a(n) = a(n-1) +a(n-2) +a(n-3).
k=2: a(n) = 3*a(n-1) +2*a(n-2) +2*a(n-3) -a(n-4) -a(n-5).
k=3: a(n) = 6*a(n-1) +5*a(n-2) +22*a(n-3) +7*a(n-4) +8*a(n-5) -18*a(n-6) -20*a(n-7) -a(n-8) +4*a(n-9) +3*a(n-10) +a(n-12).
Column k=1 for an underlying 0..z array: a(n) = sum(i=1..2z+1){a(n-i)} z=1,2,3,4

A133791 Number of n X n binary matrices with every 1 adjacent to some 0 horizontally, vertically, diagonally or antidiagonally.

Original entry on oeis.org

1, 15, 417, 50625, 24879489, 48231228511, 373654052856545, 11546079143118274625, 1422756868491071266637985, 699232611373976058162941025423, 1370556061582419558173913152072112161, 10714096395475651010921722651799661109404545
Offset: 1

Views

Author

R. H. Hardin, Jan 05 2008

Keywords

Comments

Number of dominating sets in the n X n king graph. - Andrew Howroyd, May 10 2017

Crossrefs

Main diagonal of A218663.
Cf. A133515, A133556, A063443 (independent vertex sets).

Programs

Extensions

a(12) and beyond from Christian Sievers, Dec 03 2023

A287690 Number of connected dominating sets in the n X n grid graph.

Original entry on oeis.org

1, 9, 129, 5617, 964755, 617429805, 1436456861467, 12128014243816259, 370157141019558632729, 40729998558184127557326187, 16129157077874837008807129310501, 22956060013827748812137293758719842059, 117308080543566432787532732819884994609487361
Offset: 1

Views

Author

Eric W. Weisstein, May 29 2017

Keywords

Crossrefs

Main diagonal of A291872.

Extensions

a(6)-a(13) from Andrew Howroyd, Sep 04 2017

A290382 Number of minimal dominating sets in the n X n grid graph.

Original entry on oeis.org

1, 6, 16, 306, 6958, 349178, 40307167, 8863408138, 4227470143437, 4108988275187691
Offset: 1

Views

Author

Eric W. Weisstein, Jul 28 2017

Keywords

Crossrefs

Main diagonal of A286847.
Cf. A133515 (dominating sets), A286869 (irredundant sets).

Extensions

a(5)-a(9) from Andrew Howroyd, Jul 31 2017
a(10) from Christian Sievers, Dec 03 2023

A197048 Number of n X n 0..4 arrays with each element equal to the number of its horizontal and vertical zero neighbors.

Original entry on oeis.org

1, 2, 10, 42, 358, 4468, 88056, 2745186, 134355866, 10264692132, 1234801357470, 232966546265096, 68939282741912248
Offset: 1

Views

Author

R. H. Hardin, Oct 09 2011

Keywords

Comments

Every 0 is next to 0 0's, every 1 is next to 1 0's, every 2 is next to 2 0's, every 3 is next to 3 0's, every 4 is next to 4 0's.
Also, the number of maximal independent vertex sets in the grid graph P_n X P_n. - Andrew Howroyd, May 16 2017

Examples

			Some solutions for n=4
..0..2..0..2....2..0..1..1....2..0..3..0....0..3..0..2....1..0..3..0
..1..1..2..0....0..3..1..0....0..4..0..2....3..0..3..0....1..2..0..3
..2..0..2..1....3..0..2..1....3..0..2..1....0..2..1..1....0..1..3..0
..0..3..0..1....0..3..0..1....0..2..1..0....1..1..0..1....1..1..0..2
		

Crossrefs

Diagonal of A197054.
Cf. A006506 (independent vertex sets), A133515 (dominating sets).

Programs

A347632 Number of minimum dominating sets in the n X n grid graph.

Original entry on oeis.org

1, 6, 10, 2, 22, 288, 2, 52, 32, 4, 32, 21600, 18, 540360, 34528, 100406, 70266144, 1380216154, 1682689266, 77900162, 233645826, 200997249200
Offset: 1

Views

Author

Eric W. Weisstein, Sep 09 2021

Keywords

Crossrefs

Main diagonal of A350820.
Cf. A104519 (domination number), A133515 (dominating sets), A290382 (minimal dominating sets).

Extensions

a(7)-a(12) from Andrew Howroyd, Jan 17 2022
a(13)-a(22) from Stephan Mertens, Aug 18 2024

A133556 Number of n X n binary matrices with every 1 diagonally or antidiagonally adjacent to some 0.

Original entry on oeis.org

1, 9, 187, 11881, 3720993, 4652194849, 21048197450115, 362982575751004609, 24187438805159042241345, 6154694340999818634869088969, 5974124007380479364088559506443355
Offset: 1

Views

Author

R. H. Hardin, Dec 25 2007

Keywords

Comments

Number of dominating sets in the direct product of the graphs P_n and P_n. - Andrew Howroyd, May 10 2017

Crossrefs

A378412 Irregular triangle read by rows: T(n,k) is the coefficient of x^k in the domination polynomial of the n X n grid graph (n>=1, A104519(n+2)<=k<=n^2).

Original entry on oeis.org

1, 6, 4, 1, 10, 57, 98, 80, 36, 9, 1, 2, 40, 554, 2484, 5494, 7268, 6402, 3964, 1760, 556, 120, 16, 1, 22, 1545, 22594, 140304, 492506, 1126091, 1823057, 2204694, 2063202, 1528544, 908623, 435832, 168426, 51953, 12550, 2296, 300, 25, 1, 288, 20896, 478624
Offset: 1

Views

Author

Eric W. Weisstein, Nov 25 2024

Keywords

Comments

Sum_{k=A104519(n+2)..n^2} T(n,k) = A133515(n).
T(n,n^2) = 1.

Examples

			D_1(x)=x
D_2(x)=6*x^2+4*x^3+x^4
D_3(x)=10*x^3+57*x^4+98*x^5+80*x^6+36*x^7+9*x^8+x^9
D_4(x)=2*x^4+40*x^5+554*x^6+2484*x^7+5494*x^8+7268*x^9+6402*x^10+3964*x^11+1760*x^12+556*x^13+120*x^14+16*x^15+x^16
		

Crossrefs

Cf. A104519 (domination number of the (n-2) X (n-2) grid graph).
Cf. A133515 (number of dominating sets in the n X n grid graph).
Cf. A000290 (vertex count of the n X n grid graph = n^2).
Showing 1-8 of 8 results.