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 A220623 Number of ways to reciprocally link elements of an 4Xn array either to themselves or to exactly one horizontal, diagonal and antidiagonal neighbor 1
 1, 71, 765, 17084, 282777, 5280827, 93905509, 1703300073, 30648000256, 553256525421, 9974206108397, 179912817659011, 3244530759637569, 58516690759430228, 1055339507419304093, 19033159346284815815 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Row 4 of A220621 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 14*a(n-1) +98*a(n-2) -452*a(n-3) -102*a(n-4) +876*a(n-5) -144*a(n-6) -268*a(n-7) +22*a(n-8) -8*a(n-9) +15*a(n-10) EXAMPLE Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10) ..0..6..4....6..4..0....6..4..0....0..6..4....0..7..0....0..0..7....9..9..0 ..0..6..4....6..4..0....0..9..0....0..9..0....3..9..0....0..3..0....0..1..1 ..0..7..7....0..0..0....9..0..1....0..0..1....0..0..1....9..7..0....6..4..0 ..3..3..0....0..6..4....0..1..0....0..0..0....6..4..0....3..1..0....6..4..0 CROSSREFS Sequence in context: A201039 A142674 A089706 * A173806 A253683 A210699 Adjacent sequences:  A220620 A220621 A220622 * A220624 A220625 A220626 KEYWORD nonn AUTHOR R. H. Hardin Dec 17 2012 STATUS approved

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Last modified June 17 19:10 EDT 2019. Contains 324198 sequences. (Running on oeis4.)