A220688 T(n,k)=Number of ways to reciprocally link elements of an nXk array either to themselves or to exactly two horizontal, vertical or antidiagonal neighbors.

1, 1, 1, 1, 4, 1, 1, 12, 12, 1, 1, 37, 94, 37, 1, 1, 114, 745, 745, 114, 1, 1, 351, 5851, 15452, 5851, 351, 1, 1, 1081, 46027, 312603, 312603, 46027, 1081, 1, 1, 3329, 362057, 6349886, 15978924, 6349886, 362057, 3329, 1, 1, 10252, 2847943, 128995678

Offset: 1

Author

R. H. Hardin Dec 17 2012

Keywords

• nonn
• tabl

Comments

Table starts

.1.....1.........1.............1................1....................1

.1.....4........12............37..............114..................351

.1....12........94...........745.............5851................46027

.1....37.......745.........15452...........312603..............6349886

.1...114......5851........312603.........15978924............822649205

.1...351.....46027.......6349886........822649205.........107713940118

.1..1081....362057.....128995678......42362190063.......14108684022136

.1..3329...2847943....2620320833....2181341369109.....1848014307847883

.1.10252..22401961...53226950200..112319870453715...242044667782801540

.1.31572.176214299.1081210102382.5783510938076077.31702119421997470360

Examples

			Some solutions for n=3 k=4 0=self 2=n 3=ne 4=w 6=e 7=sw 8=s (reciprocal directions total 10)
.00.78.00.00...68.46.47.00...00.78.78.00...68.46.46.47...68.46.47.00
.38.26.46.48...28.37.67.48...38.23.27.78...28.67.34.78...28.38.00.78
.26.46.46.24...23.36.46.24...26.34.36.24...23.00.36.24...26.24.36.24
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..180

Crossrefs

Column 2 is A099098