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.

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A208085 T(n,k)=Number of (n+1)X(k+1) 0..1 arrays with every 2X2 subblock having the same number of equal edges as its horizontal neighbors and a different number from its vertical neighbors, and new values 0..1 introduced in row major order.

Original entry on oeis.org

8, 20, 12, 56, 20, 24, 164, 32, 56, 36, 488, 52, 134, 60, 72, 1460, 84, 344, 96, 168, 108, 4376, 136, 888, 156, 402, 180, 216, 13124, 220, 2318, 252, 1032, 288, 504, 324, 39368, 356, 6056, 408, 2664, 468, 1206, 540, 648, 118100, 576, 15848, 660, 6954, 756, 3096
Offset: 1

Views

Author

R. H. Hardin Feb 23 2012

Keywords

Comments

Table starts
...8..20...56..164..488..1460..4376..13124..39368.118100..354296.1062884
..12..20...32...52...84...136...220....356....576....932....1508....2440
..24..56..134..344..888..2318..6056..15848..41478.108584..284264..744206
..36..60...96..156..252...408...660...1068...1728...2796....4524....7320
..72.168..402.1032.2664..6954.18168..47544.124434.325752..852792.2232618
.108.180..288..468..756..1224..1980...3204...5184...8388...13572...21960
.216.504.1206.3096.7992.20862.54504.142632.373302.977256.2558376.6697854
.324.540..864.1404.2268..3672..5940...9612..15552..25164...40716...65880

Examples

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

Crossrefs

Column 1 is A153339(n+2).
Row 1 is A115099.
Row 2 is A022087(n+3).
Row 4 is A022346(n+3).

Formula

Empirical for column k:
k=1: a(n) = 3*a(n-2)
k=2..7: a(n) = 3*a(n-2) for n>3
Empirical for row n:
n=1: a(k)=4*a(k-1)-3*a(k-2)
n=2,4,6: a(k)=a(k-1)+a(k-2)
n=3,5,7: a(k)=3*a(k-1)-3*a(k-3)+a(k-4)

A208780 T(n,k)=Number of nXk 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 1 1 and 1 1 1 vertically.

Original entry on oeis.org

2, 4, 4, 6, 16, 6, 10, 36, 36, 10, 16, 100, 36, 100, 16, 26, 256, 60, 60, 256, 26, 42, 676, 96, 100, 96, 676, 42, 68, 1764, 156, 160, 160, 156, 1764, 68, 110, 4624, 252, 260, 256, 260, 252, 4624, 110, 178, 12100, 408, 420, 416, 416, 420, 408, 12100, 178, 288, 31684, 660
Offset: 1

Views

Author

R. H. Hardin Mar 01 2012

Keywords

Comments

Table starts
..2....4...6..10...16...26...42...68...110...178...288....466....754....1220
..4...16..36.100..256..676.1764.4624.12100.31684.82944.217156.568516.1488400
..6...36..36..60...96..156..252..408...660..1068..1728...2796...4524....7320
.10..100..60.100..160..260..420..680..1100..1780..2880...4660...7540...12200
.16..256..96.160..256..416..672.1088..1760..2848..4608...7456..12064...19520
.26..676.156.260..416..676.1092.1768..2860..4628..7488..12116..19604...31720
.42.1764.252.420..672.1092.1764.2856..4620..7476.12096..19572..31668...51240
.68.4624.408.680.1088.1768.2856.4624..7480.12104.19584..31688..51272...82960

Examples

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

Crossrefs

Column 1 is A006355(n+2)
Column 2 is A206981
Diagonal is A206981 and column 2 for n>1
Column 3 is A022346(n+1) for n>2
Column 4 is A022354(n+1) for n>2
Column 5 is A022366(n+1) for n>2

Formula

Empirical for column k:
k=1: a(n) = a(n-1) +a(n-2)
k=2: a(n) = 2*a(n-1) +2*a(n-2) -a(n-3)
k=3: a(n) = a(n-1) +a(n-2) for n>4
k=4: a(n) = a(n-1) +a(n-2) for n>4
k=5: a(n) = a(n-1) +a(n-2) for n>4
k=6: a(n) = a(n-1) +a(n-2) for n>4
k=7: a(n) = a(n-1) +a(n-2) for n>4
Showing 1-2 of 2 results.