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 1-9 of 9 results.

A218663 T(n,k) = Hilltop maps: number of n X k binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..1 n X k array.

Original entry on oeis.org

1, 3, 3, 5, 15, 5, 9, 57, 57, 9, 17, 225, 417, 225, 17, 31, 891, 3249, 3249, 891, 31, 57, 3519, 25533, 50625, 25533, 3519, 57, 105, 13905, 199489, 793881, 793881, 199489, 13905, 105, 193, 54945, 1560161, 12383361, 24879489, 12383361, 1560161, 54945
Offset: 1

Views

Author

R. H. Hardin, Nov 04 2012

Keywords

Comments

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

Examples

			Table starts
....1........3...........5...............9.................17
....3.......15..........57.............225................891
....5.......57.........417............3249..............25533
....9......225........3249...........50625.............793881
...17......891.......25533..........793881...........24879489
...31.....3519......199489........12383361..........775176415
...57....13905.....1560161.......193349025........24176619049
..105....54945....12202673......3018953025.......754066017977
..193...217107....95434773.....47135449449.....23517838102321
..355...857871...746388537....735942652641....733484062428443
..653..3389769..5837454753..11490533873361..22876204302519509
.1201.13394241.45654295713.179405691966081.713472099034206097
...
Some solutions for n=3 k=4
..1..1..1..0....1..0..1..1....0..1..0..1....0..1..1..0....1..0..0..0
..0..1..0..0....0..0..0..0....1..0..0..1....0..0..1..1....0..0..1..1
..0..1..0..1....1..1..0..1....0..1..1..1....1..1..0..1....1..1..0..0
		

Crossrefs

Columns 1-7 are A000213(n+1), A218657, A218658, A218659, A218660, A218661, A218662.
Diagonal is A133791.

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) +3*a(n-2) +3*a(n-3)
k=3: a(n) = 6*a(n-1) +11*a(n-2) +26*a(n-3) -5*a(n-4) -5*a(n-6)
k=4: a(n) = 12*a(n-1) +45*a(n-2) +180*a(n-3) -27*a(n-4) -81*a(n-6)
Columns k=1..z+1 for an underlying 0..z array: a(n) = sum(i=1..2z+1){(2^k-1)*a(n-i)} checked for z=1..3.

A289180 Number of connected dominating sets in the n X n king graph.

Original entry on oeis.org

1, 15, 336, 29648, 11293568, 17784998912, 113637188081536, 2924018436019899392, 301641905727809350974464, 124378420721322865523465096192, 204571358406088229163099037060664832, 1340178778197906145868721021815647098466816
Offset: 1

Views

Author

Eric W. Weisstein, Jun 27 2017

Keywords

Crossrefs

Main diagonal of A291873.

Extensions

a(6)-a(12) from Andrew Howroyd, Sep 04 2017

A303116 Number of total dominating sets in the n X n king graph.

Original entry on oeis.org

0, 11, 353, 35458, 16322279, 30158547693, 217221533288240, 6223220939472363571, 709791800918008570287847, 321673400252458591521699180612, 579292884621843116328602359172702605, 4146239141804826663870561644604700888044071
Offset: 1

Views

Author

Andrew Howroyd, Apr 18 2018

Keywords

Crossrefs

Main diagonal of A303114.

A347554 Number of minimum dominating sets in the n X n king graph.

Original entry on oeis.org

1, 4, 1, 256, 79, 1, 243856, 3600, 1, 581571283, 281585, 1, 2722291223553, 32581328, 1, 21706368614058886, 5112264019, 1, 268740319616196074546, 1028516654620, 1, 4839916638142874877046813
Offset: 1

Views

Author

Eric W. Weisstein, Sep 06 2021

Keywords

Comments

a(3*n) = 1 for all n, since the 3n X 3n king graph has domination number n^2 and the only way to achieve this is if each of the n^2 kings is placed in the middle of its own 3 X 3 square.

Crossrefs

Main diagonal of A350815.
Cf. A075561 (domination number of the n X n king graph), A133791, A286881.

Extensions

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

A286881 Number of minimal dominating sets in the n X n king graph.

Original entry on oeis.org

1, 4, 12, 256, 971, 85405, 1997448, 360584008, 34097946429, 16133593980207, 8445394800836595, 9548578220258420637
Offset: 1

Views

Author

Eric W. Weisstein, Aug 02 2017

Keywords

Crossrefs

Main diagonal of A286849.
Cf. A133791 (dominating sets), A286871 (irredundant sets).
Cf. A290382 (grid graph).

Extensions

a(5)-a(9) from Andrew Howroyd, Aug 03 2017
a(10)-a(12) from Christian Sievers, Dec 01 2023

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

A175563 Number of n X n binary matrices that contain no 2 X 2 zero submatrix.

Original entry on oeis.org

1, 2, 15, 334, 18521, 2293896, 586774783, 292184148320, 270280183791969, 447043237292379520, 1280479639717884356831, 6180626271969237488205312
Offset: 0

Views

Author

Max Alekseyev, Jul 03 2010

Keywords

Crossrefs

Formula

E.g.f.: the diagonal of exp( Sum_B x^|lB| * y^|rB| / |Aut(B,lB,rB)| ), where B runs over connected squarefree bipartite graphs with ordered bipartitions, (lB,rB) is the bipartition of B, and Aut(B,lB,rB) is the group of automorphisms of B preserving its bipartition.

Extensions

a(6)-a(8) from Hiroaki Yamanouchi, Aug 27 2014
a(9)-a(11) from Max Alekseyev, Feb 26 2022

A288956 Number of maximal independent vertex sets (and minimal vertex covers) in the n X n king graph.

Original entry on oeis.org

1, 4, 8, 79, 544, 8197, 201611, 6214593, 391918650, 32239887128, 4599025630995, 1018245217588836, 346578151637999287, 193445218205732588935, 165199496607694525364163, 226636538088997406396236072, 488063150616514603623041818756, 1655950305544572458601638523072809
Offset: 1

Views

Author

Eric W. Weisstein, Jun 20 2017

Keywords

Crossrefs

Main diagonal of A332347.
Cf. A197048 (grid graph), A063443 (independent sets), A193580, A133791 (dominating sets).

Extensions

a(9)-a(18) from Andrew Howroyd, Jun 26 2017

A378420 Irregular triangle read by rows: T(n,k) is the coefficient of x^k in the domination polynomial of the n X n king graph (n>=1, A075561(n)<=k<=n^2).

Original entry on oeis.org

1, 4, 6, 4, 1, 1, 10, 48, 106, 122, 84, 36, 9, 1, 256, 1536, 4480, 8320, 10896, 10560, 7744, 4320, 1816, 560, 120, 16, 1, 79, 1593, 14672, 81524, 307244, 842506, 1764068, 2918828, 3909834, 4311034, 3955232, 3038092, 1957940, 1056965, 475304, 176256, 53046, 12646
Offset: 1

Views

Author

Eric W. Weisstein, Nov 25 2024

Keywords

Comments

Sum_{k=A075561(n)..n^2} T(n,k) = A133791(n).
T(n,n^2) = 1.

Examples

			D(1)=x
D(2)=4*x+6*x^2+4*x^3+x^4
D(3)=x+10*x^2+48*x^3+106*x^4+122*x^5+84*x^6+36*x^7+9*x^8+x^9
D(4)=256*x^4+1536*x^5+4480*x^6+8320*x^7+10896*x^8+10560*x^9+7744*x^10+4320*x^11+1816*x^12+560*x^13+120*x^14+16*x^15+x^16
		

Crossrefs

Cf. A075561 (domination number of the n X n king graph).
Cf. A133791 (number of dominating sets in the n X n king graph).
Cf. A000290 (vertex count of the n X n king graph = n^2).
Showing 1-9 of 9 results.