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.

A228482 T(n,k)=Number of nXk binary arrays with top left value 1 and no two ones adjacent horizontally, vertically or antidiagonally.

Original entry on oeis.org

1, 1, 1, 2, 2, 2, 3, 4, 4, 3, 5, 9, 14, 9, 5, 8, 19, 41, 41, 19, 8, 13, 41, 127, 172, 127, 41, 13, 21, 88, 386, 728, 728, 386, 88, 21, 34, 189, 1181, 3084, 4354, 3084, 1181, 189, 34, 55, 406, 3605, 13050, 25699, 25699, 13050, 3605, 406, 55, 89, 872, 11013, 55252, 152373
Offset: 1

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Author

R. H. Hardin Aug 22 2013

Keywords

Comments

Table starts
..1...1.....2......3.......5.........8.........13..........21............34
..1...2.....4......9......19........41.........88.........189...........406
..2...4....14.....41.....127.......386.......1181........3605.........11013
..3...9....41....172.....728......3084......13050.......55252........233875
..5..19...127....728....4354.....25699.....152373......902042.......5342712
..8..41...386...3084...25699....211588....1748684....14433982.....119188751
.13..88..1181..13050..152373...1748684...20185842...232542935....2680777055
.21.189..3605..55252..902042..14433982..232542935..3737615288...60122232373
.34.406.11013.233875.5342712.119188751.2680777055.60122232373.1349721589622
Same recurrences as A228285 except in addition this smaller one for k=5

Examples

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

Crossrefs

Column 1 is A000045
Column 2 is A078039(n-1).

Formula

Recurrences for column k:
k=1: a(n) = a(n-1) +a(n-2)
k=2: a(n) = a(n-1) +2*a(n-2) +a(n-3)
k=3: a(n) = a(n-1) +5*a(n-2) +4*a(n-3) -a(n-5)
k=4: a(n) = a(n-1) +10*a(n-2) +15*a(n-3) +4*a(n-4) -6*a(n-5) -a(n-6) +3*a(n-7) -a(n-8)
k=5: a(n) = 3*a(n-1) +15*a(n-2) +16*a(n-3) -11*a(n-4) -20*a(n-5) +19*a(n-6) -8*a(n-7) +a(n-9)
k=6: a(n) = a(n-1) +42*a(n-2) +147*a(n-3) +70*a(n-4) -478*a(n-5) -449*a(n-6) +1199*a(n-7) +732*a(n-8) -2727*a(n-9) +659*a(n-10) +3827*a(n-11) -5776*a(n-12) +3926*a(n-13) -1152*a(n-14) -148*a(n-15) +154*a(n-16) +32*a(n-17) -29*a(n-18) -6*a(n-19) +3*a(n-20) +a(n-21)
k=7: a(n) = a(n-1) +85*a(n-2) +432*a(n-3) +192*a(n-4) -3711*a(n-5) -5096*a(n-6) +21164*a(n-7) +27340*a(n-8) -112654*a(n-9) -37244*a(n-10) +477721*a(n-11) -464722*a(n-12) -897815*a(n-13) +3102284*a(n-14) -4149918*a(n-15) +2761082*a(n-16) -138325*a(n-17) -1353257*a(n-18) +942033*a(n-19) +64683*a(n-20) -365483*a(n-21) +80904*a(n-22) +92350*a(n-23) -27097*a(n-24) -23292*a(n-25) +2585*a(n-26) +5635*a(n-27) +1405*a(n-28) -561*a(n-29) -545*a(n-30) -173*a(n-31) -14*a(n-32) +5*a(n-33) +a(n-34)