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.

A183304 Half the number of n X 3 binary arrays with no element equal to a strict majority of its horizontal and vertical neighbors.

Original entry on oeis.org

1, 4, 9, 19, 42, 93, 205, 452, 997, 2199, 4850, 10697, 23593, 52036, 114769, 253131, 558298, 1231365, 2715861, 5990020, 13211405, 29138671, 64267362, 141746129, 312630929, 689529220, 1520804569, 3354240067, 7398009354, 16316823277
Offset: 1

Views

Author

R. H. Hardin, Jan 03 2011

Keywords

Examples

			Some solutions with a(1,1)=0 for 3X4
..0..1..0..1....0..0..1..1....0..1..0..1....0..1..0..0....0..1..1..0
..1..0..0..1....1..1..0..0....0..1..1..0....1..0..1..1....1..0..0..1
..0..1..1..0....0..1..0..1....1..0..1..0....0..1..0..0....0..1..1..0
		

Crossrefs

Column 3 of A183312.

Formula

Empirical: a(n) = 2*a(n-1)+a(n-3).
Empirical G.f.: x*(1+x)^2/(1-2*x-x^3). - Colin Barker, Feb 23 2012

A183305 Half the number of nX4 binary arrays with no element equal to a strict majority of its horizontal and vertical neighbors.

Original entry on oeis.org

2, 6, 19, 55, 178, 572, 1798, 5700, 18064, 57249, 181433, 574924, 1821857, 5773450, 18295845, 57978643, 183731482, 582236576, 1845081304, 5846978390, 18528805856, 58716935815, 186071279593, 589651361292, 1868578146701, 5921438527588
Offset: 1

Views

Author

R. H. Hardin Jan 03 2011

Keywords

Comments

Column 4 of A183312

Examples

			Some solutions with a(1,1)=0 for 4X4
..0..1..0..1....0..1..1..0....0..0..1..0....0..1..0..0....0..1..0..1
..1..0..1..0....1..0..0..1....1..1..0..1....1..0..1..1....0..1..1..0
..0..1..1..0....0..0..1..0....0..1..1..0....0..0..1..0....1..0..1..1
..0..1..0..1....1..1..0..1....1..0..0..1....1..1..0..1....0..1..0..0
		

Formula

Empirical: a(n)=5*a(n-1)-6*a(n-2)+a(n-3)+a(n-4)-9*a(n-5)+4*a(n-6)+a(n-7)+28*a(n-8)-16*a(n-9)-3*a(n-10)+2*a(n-11)-6*a(n-12)+2*a(n-13)-a(n-14) for n>15

A183306 Half the number of nX5 binary arrays with no element equal to a strict majority of its horizontal and vertical neighbors.

Original entry on oeis.org

3, 9, 42, 178, 910, 4212, 19899, 94217, 445859, 2113257, 10006598, 47387904, 224418390, 1062810762, 5033385029, 23837475807, 112891241315, 534638647159, 2531982065694, 11991154349342, 56788620500294, 268943860673076
Offset: 1

Views

Author

R. H. Hardin Jan 03 2011

Keywords

Comments

Column 5 of A183312

Examples

			Some solutions with a(1,1)=0 for 5X4
..0..0..1..0....0..1..1..0....0..1..0..1....0..1..1..0....0..1..0..1
..1..1..0..1....1..0..0..1....0..1..0..0....1..0..0..1....1..0..0..1
..0..1..1..0....0..1..1..0....1..0..1..1....1..0..0..1....0..1..1..0
..1..0..0..1....1..0..0..1....0..1..1..0....0..1..1..0....1..0..1..1
..1..0..1..0....0..1..0..1....1..0..0..1....1..0..1..0....0..1..0..0
		

Formula

Empirical: a(n)=9*a(n-1)-26*a(n-2)+24*a(n-3)+47*a(n-4)-157*a(n-5)-43*a(n-6)+641*a(n-7)-643*a(n-8)-952*a(n-9)+3460*a(n-10)-2021*a(n-11)-2111*a(n-12)+2715*a(n-13)-1249*a(n-14)-4657*a(n-15)-1514*a(n-16)+1961*a(n-17)-1230*a(n-18)+6713*a(n-19)+8832*a(n-20)+10212*a(n-21)+1971*a(n-22)-6552*a(n-23)-2819*a(n-24)-2898*a(n-25)-973*a(n-26)+302*a(n-27)+433*a(n-28)+286*a(n-29) for n>31

A183307 Half the number of nX6 binary arrays with no element equal to a strict majority of its horizontal and vertical neighbors.

Original entry on oeis.org

5, 14, 93, 572, 4212, 29400, 206755, 1447110, 10149621, 71244598, 500184679, 3512112015, 24658885220, 173129289198, 1215525172167, 8534122345666, 59917715208287, 420680331462689, 2953583636803146, 20737016295243029
Offset: 1

Views

Author

R. H. Hardin Jan 03 2011

Keywords

Comments

Column 6 of A183312

Examples

			Some solutions with a(1,1)=0 for 6X4
..0..0..1..0....0..1..0..1....0..1..0..1....0..1..0..0....0..1..0..1
..1..1..0..1....1..0..1..0....0..1..0..0....1..0..1..1....1..1..0..1
..0..1..0..0....1..0..0..1....1..0..1..1....0..0..1..0....0..0..1..0
..1..0..1..1....0..1..1..0....0..1..1..0....1..1..0..1....1..1..0..1
..0..1..0..0....1..0..0..1....1..0..0..1....0..1..0..0....0..0..1..0
..1..0..1..1....1..0..1..0....0..1..1..0....1..0..1..1....1..0..1..0
		

Programs

  • Maple
    Allowed:= proc(a)
      if nops({a[1],a[2],a[7]})=1 or nops({a[1],a[2],a[3],a[8]})=1
      or nops({a[2],a[3],a[4],a[9]})=1 or nops({a[3],a[4],a[5],a[10]})=1
      or nops({a[4],a[5],a[6],a[11]})=1 or nops({a[5],a[6],a[12]})=1
      or nops({a[1],a[7],a[8]})=1 or nops({a[2],a[7],a[8],a[9]})=1
      or nops({a[3],a[8],a[9],a[10]})=1 or nops({a[4],a[9],a[10],a[11]})=1
      or nops({a[5],a[10],a[11],a[12]})=1 or nops({a[6],a[11],a[12]})=1
      then false else true fi
    end proc:
    Configs:= select(Allowed,[seq(convert(n,base,2)[1..12],n=2^12..2^13-1)]):
    Compatible:= proc(i,j) local Xi,Xj,k;
     Xi:= map(t -> 2*t-1,Configs[i]); Xj:= map(t -> 2*t-1,Configs[j]);
     if Xi[7..12] <> Xj[1..6] then return 0 fi;
     if Xi[7] = signum(Xi[1]+Xi[8]+Xj[7]) then return 0 fi;
     for k from 8 to 11 do if Xi[k] = signum(Xi[k-6]+Xi[k-1]+Xi[k+1]+Xj[k]) then return 0 fi od;
     if Xi[12] = signum(Xi[6]+Xi[11]+Xj[12]) then return 0 fi;
     1
    end proc:
    T:= Matrix(722,722,Compatible):
    uok:= proc(i) local a,k;
       a:= map(t -> 2*t-1, Configs[i]);
       for k from 2 to 5 do if a[k] = signum(a[k-1]+a[k+1]+a[k+6]) then return 0 fi od;
       1
    end proc:
    u:= Vector(722, uok):
    vok:= proc(i) local a,k;
        a:= map(t -> 2*t-1, Configs[i]);
        for k from 8 to 11 do if a[k] = signum(a[k-1]+a[k+1]+a[k-6]) then return 0 fi od;
        1
    end proc:
    v:= Vector(722,vok):
    Tv[0]:= v:
    for nn from 1 to 50 do Tv[nn]:= T . Tv[nn-1] od:
    A:= [10, seq(u^%T . Tv[n],n=0..50)]/2:
    A[1..50]; # Robert Israel, Oct 23 2019

Formula

Linear recurrence of order 93 for n >= 95: see links. - Robert Israel, Oct 23 2019

A183308 Half the number of nX7 binary arrays with no element equal to a strict majority of its horizontal and vertical neighbors.

Original entry on oeis.org

8, 22, 205, 1798, 19899, 206755, 2160250, 22504107, 234636215, 2447317278, 25539919635, 266563403686, 2782185688787, 29038350922976, 303075629656107, 3163217395827118, 33014647369487612, 344575588242732515
Offset: 1

Views

Author

R. H. Hardin Jan 03 2011

Keywords

Comments

Column 7 of A183312

Examples

			Some solutions with a(1,1)=0 for 7X4
..0..1..0..1....0..1..0..1....0..0..1..0....0..1..0..1....0..1..0..1
..1..0..0..1....1..0..1..0....1..1..0..1....0..1..0..1....0..1..0..1
..1..0..1..0....1..0..1..0....0..1..0..1....1..0..1..0....1..1..0..0
..0..1..0..1....0..1..0..1....1..0..1..0....0..1..1..0....0..0..1..1
..0..1..0..0....1..1..0..1....0..1..0..1....0..1..0..1....1..1..0..0
..1..0..1..1....0..0..1..0....1..1..0..0....1..0..0..1....0..1..0..1
..1..0..1..0....1..0..1..0....0..0..1..1....0..1..1..0....1..0..1..0
		

A183309 Half the number of nX8 binary arrays with no element equal to a strict majority of its horizontal and vertical neighbors.

Original entry on oeis.org

13, 35, 452, 5700, 94217, 1447110, 22504107, 348871589, 5406312318, 83828453334, 1300167830235, 20168484726903, 312884691407215, 4853992391306949, 75303212625271575, 1168225180318165057, 18123347504407854750
Offset: 1

Views

Author

R. H. Hardin Jan 03 2011

Keywords

Comments

Column 8 of A183312

Examples

			Some solutions with a(1,1)=0 for 8X4
..0..1..0..0....0..0..1..0....0..1..1..0....0..0..1..1....0..1..1..0
..1..0..1..1....1..1..0..1....1..0..0..1....1..1..0..0....1..0..0..1
..1..0..1..0....0..0..0..1....0..0..1..0....0..0..1..1....0..1..0..1
..0..1..0..1....1..1..1..0....1..1..0..1....1..1..0..0....1..0..1..0
..1..0..1..0....0..0..1..0....0..1..1..0....0..0..1..1....1..0..0..1
..1..0..0..1....1..0..0..1....1..0..1..0....1..1..0..0....0..1..1..0
..0..1..0..0....0..1..1..0....0..1..0..1....0..1..0..1....1..1..0..1
..1..0..1..1....1..0..0..1....1..0..1..0....0..1..0..1....0..0..1..0
		

A183310 Half the number of nX9 binary arrays with no element equal to a strict majority of its horizontal and vertical neighbors.

Original entry on oeis.org

21, 56, 997, 18064, 445859, 10149621, 234636215, 5406312318, 124597748299, 2872365166632, 66225579904258, 1527174330126193, 35219108887364016, 812230463677554629, 18731997169049673477, 432004778124039265271
Offset: 1

Views

Author

R. H. Hardin Jan 03 2011

Keywords

Comments

Column 9 of A183312

Examples

			Some solutions with a(1,1)=0 for 9X4
..0..1..0..1....0..0..1..0....0..0..1..0....0..1..0..1....0..1..0..1
..1..1..0..1....1..1..0..1....1..1..0..1....1..1..0..1....1..1..0..0
..0..0..1..0....0..0..1..0....0..1..0..1....0..0..1..0....0..0..1..1
..1..1..1..0....1..0..0..1....1..0..1..0....1..1..0..1....1..1..0..0
..0..0..0..1....0..1..1..0....1..0..0..1....0..0..1..0....0..1..0..1
..1..1..1..0....1..0..1..0....0..1..1..0....1..1..1..0....0..1..1..0
..0..0..0..1....0..1..0..1....1..0..0..1....0..0..0..1....1..0..1..1
..1..1..0..1....1..1..0..0....0..0..1..0....1..1..1..0....0..1..0..0
..0..0..1..0....0..0..1..1....1..1..0..1....0..0..1..0....1..0..1..1
		

A183311 Half the number of n X 10 binary arrays with no element equal to a strict majority of its horizontal and vertical neighbors.

Original entry on oeis.org

34, 90, 2199, 57249, 2113257, 71244598, 2447317278, 83828453334, 2872365166632, 98443712937832, 3374443074400317, 115681374040641527, 3965953010347657340, 135970823441576045577, 4661739412614625916040, 159827567992214512088271
Offset: 1

Views

Author

R. H. Hardin, Jan 03 2011

Keywords

Comments

Column 10 of A183312.

Examples

			Some solutions with a(1,1)=0 for 10 X 4
..0..1..0..1....0..0..1..0....0..1..0..0....0..1..1..0....0..1..0..1
..1..0..0..1....1..1..0..1....1..0..1..1....1..0..0..1....0..1..1..0
..1..0..1..0....0..1..0..0....1..0..1..0....0..1..0..0....1..0..0..1
..0..1..1..0....1..0..1..1....0..1..0..1....1..0..1..1....0..1..1..0
..1..0..0..1....0..1..1..0....1..0..0..1....0..1..1..0....1..0..0..1
..1..0..0..1....0..1..0..1....0..1..1..0....1..0..0..1....0..1..0..1
..0..1..1..0....1..0..1..0....1..0..1..0....0..1..1..0....0..1..1..0
..1..0..1..0....1..0..1..1....1..0..1..1....1..1..0..1....1..0..0..1
..1..0..1..1....0..1..0..0....0..1..0..0....0..0..1..0....0..1..1..0
..0..1..0..0....0..1..0..1....0..1..0..1....1..1..0..1....0..1..0..1
		

Crossrefs

Cf. A183312.

A183303 Half the number of n X n binary arrays with no element equal to a strict majority of its horizontal and vertical neighbors.

Original entry on oeis.org

1, 3, 9, 55, 910, 29400, 2160250, 348871589, 124597748299, 98443712937832, 171962948531581497, 664040284641624620852, 5667787901436816984441067
Offset: 1

Views

Author

R. H. Hardin Jan 03 2011

Keywords

Comments

Diagonal of A183312

Examples

			Some solutions with a(1,1)=0 for 5X5
..0..1..0..1..0....0..1..0..1..0....0..1..0..1..0....0..1..0..0..1
..0..1..0..1..0....0..1..0..0..1....0..1..0..0..1....1..0..1..1..0
..1..1..0..0..1....1..0..1..0..1....1..0..1..0..1....0..1..1..0..1
..0..0..1..1..0....0..0..1..1..0....1..0..1..1..0....0..1..0..1..0
..1..0..1..0..1....1..1..0..1..0....0..1..0..0..1....1..0..1..0..1
		
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