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 A220744 Number of ways to reciprocally link elements of an 7 X n array either to themselves or to exactly two horizontal, diagonal and antidiagonal neighbors, without consecutive collinear links. 0
 1, 64, 3403, 355883, 32924133, 3287610473, 319803318494, 31411054258761, 3063698245151388 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Row 7 of A220738. LINKS Table of n, a(n) for n=1..9. EXAMPLE Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10) .00.00.00...00.79.00...00.69.47...00.67.47...00.00.00...69.49.00...00.67.47 .00.00.00...39.69.14...00.36.14...39.39.00...00.67.47...00.17.17...36.34.00 .00.79.00...00.16.14...00.69.47...00.17.17...36.34.00...36.34.00...00.00.00 .39.79.17...69.47.00...00.36.14...36.34.00...69.49.00...69.47.00...00.69.47 .39.13.17...36.14.00...00.79.00...69.47.00...69.14.17...36.14.00...00.36.14 .00.13.00...69.47.00...39.69.14...39.17.00...00.13.00...69.47.00...00.00.00 .00.00.00...36.14.00...00.16.14...36.14.00...00.00.00...36.14.00...00.00.00 CROSSREFS Cf. A220738. Sequence in context: A299179 A299941 A017439 * A298194 A299088 A299344 Adjacent sequences: A220741 A220742 A220743 * A220745 A220746 A220747 KEYWORD nonn AUTHOR R. H. Hardin, Dec 18 2012 STATUS approved

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Last modified September 21 11:35 EDT 2023. Contains 365501 sequences. (Running on oeis4.)