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 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 7
 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 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 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 LINKS R. H. Hardin, Table of n, a(n) for n = 1..180 EXAMPLE 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 CROSSREFS Column 2 is A099098 Sequence in context: A099759 A072590 A111636 * A146990 A051433 A163366 Adjacent sequences:  A220685 A220686 A220687 * A220689 A220690 A220691 KEYWORD nonn,tabl AUTHOR R. H. Hardin Dec 17 2012 STATUS approved

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Last modified September 20 17:16 EDT 2020. Contains 337265 sequences. (Running on oeis4.)