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 A220617 Number of ways to reciprocally link elements of an nX4 array either to themselves or to exactly one horizontal, diagonal and antidiagonal neighbor 1
 5, 87, 1189, 17084, 243119, 3466455, 49406943, 704243629, 10038098456, 143080761421, 2039439299333, 29069688249415, 414352491974681, 5906082889319188, 84183915242486395, 1199937711608731991 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 4 of A220621 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 16*a(n-1) -18*a(n-2) -114*a(n-3) +230*a(n-4) -66*a(n-5) -78*a(n-6) +48*a(n-7) -4*a(n-8) -4*a(n-9) +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..9..6..4....0..0..6..4....0..6..4..0....9..7..0..0....9..7..0..0 ..0..7..1..0....0..0..0..0....0..0..0..7....3..1..6..4....3..1..6..4 ..3..0..0..0....0..0..6..4....0..0..3..0....0..0..0..0....0..6..4..0 CROSSREFS Sequence in context: A232489 A318219 A182963 * A231702 A069948 A316727 Adjacent sequences:  A220614 A220615 A220616 * A220618 A220619 A220620 KEYWORD nonn AUTHOR R. H. Hardin Dec 17 2012 STATUS approved

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Last modified May 27 01:51 EDT 2022. Contains 354092 sequences. (Running on oeis4.)