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 1-7 of 7 results.

A183821 1/256 the number of (n+1) X 3 0..3 arrays with no 2 X 2 subblock being a reflection across the shared element pair of any horizontal or vertical neighbor.

Original entry on oeis.org

15, 813, 43947, 2377341, 128578815, 6954559893, 376152548283, 20345104031589, 1100412240703119, 59518368554767389, 3219189893127084843, 174117402720326269485, 9417546276713264441151, 509369980225226329837125
Offset: 1

Views

Author

R. H. Hardin, Jan 07 2011

Keywords

Comments

Column 2 of A183827.

Examples

			Some solutions with upper left block zero for 5 X 3:
   0 0 2   0 0 0   0 0 3   0 0 3   0 0 0   0 0 2   0 0 0
   0 0 0   0 0 1   0 0 3   0 0 2   0 0 1   0 0 1   0 0 2
   2 0 0   2 0 1   3 0 2   1 0 2   1 0 3   1 0 0   3 0 1
   2 2 1   3 2 3   1 3 1   1 3 1   0 3 3   2 1 2   0 3 3
   3 2 3   0 0 3   0 0 3   2 0 3   3 2 2   0 0 3   2 2 0
		

Crossrefs

Cf. A183827.

Programs

  • Maple
    Configs:= remove(t -> [t[1],t[4]]=[t[3],t[6]], [seq(convert(4^6+i,base,4)[1..6],i=0..4^6-1)]): nConfigs:= nops(Configs):
    Compatible:= proc(i,j) local k;
    if Configs[i][4..6] <> Configs[j][1..3] or Configs[i][1..2] =Configs[j][4..5] or Configs[i][2..3] = Configs[j][5..6] then 0 else 1 fi;
    end proc:
    T:= Matrix(nConfigs,nConfigs,Compatible):
    u:= Vector(nConfigs,1):
    Tu[0]:= u:
    for n from 1 to 30 do Tu[n]:= T . Tu[n-1] od:
    seq(u^%T . Tu[n]/256, n=0..30); # Robert Israel, Aug 10 2018

Formula

Empirical: a(n) = 43*a(n-1) + 645*a(n-2) - 2451*a(n-3).
Empirical g.f.: 3*x*(5 + 56*x - 229*x^2) / (1 - 43*x - 645*x^2 + 2451*x^3). - Colin Barker, Apr 05 2018
Empirical formulas verified (see link). - Robert Israel, Aug 10 2018

A183820 1/256 the number of (n+1)X(n+1) 0..3 arrays with no 2X2 subblock being a reflection across the shared element pair of any horizontal or vertical neighbor.

Original entry on oeis.org

1, 813, 8538066, 1163575148283, 2051388696859571241
Offset: 1

Views

Author

R. H. Hardin Jan 07 2011

Keywords

Comments

Diagonal of A183827

Examples

			Some solutions with upper left block zero for 3X3
..0..0..1....0..0..3....0..0..1....0..0..0....0..0..3....0..0..1....0..0..3
..0..0..0....0..0..3....0..0..0....0..0..3....0..0..2....0..0..3....0..0..3
..1..1..3....2..1..1....0..2..1....2..1..0....2..2..2....0..2..1....1..3..1
		

A183822 1/256 the number of (n+1)X4 0..3 arrays with no 2X2 subblock being a reflection across the shared element pair of any horizontal or vertical neighbor.

Original entry on oeis.org

225, 43947, 8538066, 1661285961, 323115202755, 62851591581012, 12225396762980829, 2378005715920214025, 462553489019014423650, 89972804578123532061801, 17500904466916598194011543
Offset: 1

Views

Author

R. H. Hardin Jan 07 2011

Keywords

Comments

Column 3 of A183827

Examples

			Some solutions with upper left block zero for 3X4
..0..0..2..1....0..0..2..3....0..0..3..3....0..0..2..0....0..0..3..0
..0..0..0..0....0..0..3..2....0..0..3..0....0..0..1..3....0..0..3..2
..2..3..1..0....3..1..0..1....2..1..2..3....3..3..2..2....0..3..0..3
		

A183823 1/256 the number of (n+1)X5 0..3 arrays with no 2X2 subblock being a reflection across the shared element pair of any horizontal or vertical neighbor.

Original entry on oeis.org

3375, 2377341, 1661285961, 1163575148283, 814479338538099, 570213177028325955, 399185865558804067443, 279459103250217225077847
Offset: 1

Views

Author

R. H. Hardin Jan 07 2011

Keywords

Comments

Column 4 of A183827

Examples

			Some solutions with upper left block zero for 3X5
..0..0..2..0..2....0..0..0..0..0....0..0..2..0..0....0..0..0..0..0
..0..0..1..3..0....0..0..2..2..3....0..0..0..2..2....0..0..3..3..2
..0..2..1..2..0....3..0..1..3..3....0..2..2..1..3....2..2..3..3..3
		

A183824 1/256 the number of (n+1)X6 0..3 arrays with no 2X2 subblock being a reflection across the shared element pair of any horizontal or vertical neighbor.

Original entry on oeis.org

50625, 128578815, 323115202755, 814479338538099, 2051388696859571241, 5167876666358771202411, 13018181193595377140956551
Offset: 1

Views

Author

R. H. Hardin Jan 07 2011

Keywords

Comments

Column 5 of A183827

Examples

			Some solutions with upper left block zero for 3X6
..0..0..2..2..0..2....0..0..2..2..0..3....0..0..2..2..0..0....0..0..2..0..0..3
..0..0..0..1..0..2....0..0..0..1..0..2....0..0..0..2..0..0....0..0..0..2..0..0
..3..1..0..1..3..1....3..3..0..2..1..0....2..2..0..1..3..3....0..1..3..2..2..1
		

A183825 1/256 the number of (n+1)X7 0..3 arrays with no 2X2 subblock being a reflection across the shared element pair of any horizontal or vertical neighbor.

Original entry on oeis.org

759375, 6954559893, 62851591581012, 570213177028325955, 5167876666358771202411
Offset: 1

Views

Author

R. H. Hardin Jan 07 2011

Keywords

Comments

Column 6 of A183827

Examples

			Some solutions with upper left block zero for 3X7
..0..0..2..0..0..0..3....0..0..0..0..1..0..0....0..0..0..0..1..0..2
..0..0..2..2..0..0..0....0..0..3..2..0..0..1....0..0..1..2..0..0..1
..2..0..1..0..1..0..0....2..0..1..0..2..0..2....1..0..3..0..3..0..0
		

A183826 1/256 the number of (n+1)X8 0..3 arrays with no 2X2 subblock being a reflection across the shared element pair of any horizontal or vertical neighbor.

Original entry on oeis.org

11390625, 376152548283, 12225396762980829, 399185865558804067443, 13018181193595377140956551
Offset: 1

Views

Author

R. H. Hardin Jan 07 2011

Keywords

Comments

Column 7 of A183827

Examples

			Some solutions with upper left block zero for 3X8
..0..0..1..2..0..0..0..2....0..0..1..2..0..1..0..1....0..0..1..0..0..0..0..2
..0..0..0..3..0..0..2..2....0..0..0..3..0..3..2..2....0..0..0..1..0..0..2..1
..0..2..1..1..0..3..0..3....0..1..1..1..0..2..0..3....0..1..1..2..0..2..0..0
		
Showing 1-7 of 7 results.