login
A220725
T(n,k)=Number of ways to reciprocally link elements of an nXk array either to themselves or to exactly two horizontal, diagonal or antidiagonal neighbors
13
1, 1, 1, 1, 2, 1, 1, 7, 4, 1, 1, 21, 30, 8, 1, 1, 68, 230, 126, 16, 1, 1, 221, 1819, 2586, 534, 32, 1, 1, 717, 14466, 52189, 29310, 2275, 64, 1, 1, 2330, 114900, 1071230, 1485872, 331589, 9667, 128, 1, 1, 7571, 913187, 21914482, 78144195, 42378036, 3751888
OFFSET
1,5
COMMENTS
Table starts
.1....1........1...........1..............1................1.................1
.1....2........7..........21.............68..............221...............717
.1....4.......30.........230...........1819............14466............114900
.1....8......126........2586..........52189..........1071230..........21914482
.1...16......534.......29310........1485872.........78144195........4067687187
.1...32.....2275......331589.......42378036.......5717794568......759141297226
.1...64.....9667.....3751888.....1208447287.....418227762771...141539684300104
.1..128....41089....42452438....34459871148...30590627951201.26392338517041335
.1..256...174660...480346122...982649830527.2237516237251959
.1..512...742428..5435081884.28021037742705
.1.1024..3155820.61497557384
.1.2048.13414405
LINKS
EXAMPLE
Some solutions for n=3 k=4 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)
.00.67.49.00...00.00.67.47...00.00.67.47...00.79.67.47...00.67.49.00
.39.00.79.17...69.34.37.00...00.39.37.00...39.39.13.00...36.47.00.17
.00.13.36.14...00.13.00.00...00.36.14.00...00.16.14.00...36.46.34.00
CROSSREFS
Column 2 is A000079(n-1)
Sequence in context: A144510 A143670 A169730 * A333142 A196832 A005450
KEYWORD
nonn,tabl
AUTHOR
R. H. Hardin Dec 18 2012
STATUS
approved