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 A220565 Number of ways to reciprocally link elements of an 4Xn array either to themselves or to exactly one horizontal or antidiagonal neighbor 1
 1, 34, 292, 3966, 45966, 561636, 6743873, 81437539, 981628768, 11839220919, 142763980945, 1721628751022, 20761198193082, 250361650578082, 3019134246246588, 36408038586112352, 439048064386701057 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Row 4 of A220562 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 4*a(n-1) +84*a(n-2) +194*a(n-3) -338*a(n-4) -1077*a(n-5) +616*a(n-6) +1932*a(n-7) -788*a(n-8) -1136*a(n-9) +325*a(n-10) +284*a(n-11) -48*a(n-12) -30*a(n-13) +2*a(n-14) +a(n-15) EXAMPLE Some solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10) ..0..6..4....0..6..4....0..6..4....0..7..0....0..0..0....6..4..0....6..4..0 ..0..0..0....0..7..0....0..7..0....3..0..0....6..4..0....0..6..4....0..7..0 ..0..7..0....3..6..4....3..6..4....6..4..7....0..6..4....0..7..7....3..0..0 ..3..0..0....0..6..4....0..0..0....0..3..0....0..6..4....3..3..0....0..0..0 CROSSREFS Sequence in context: A209891 A027006 A156531 * A230803 A209808 A160146 Adjacent sequences:  A220562 A220563 A220564 * A220566 A220567 A220568 KEYWORD nonn AUTHOR R. H. Hardin Dec 16 2012 STATUS approved

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Last modified May 25 01:55 EDT 2019. Contains 323534 sequences. (Running on oeis4.)