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 A220549 Number of ways to reciprocally link elements of an nX4 array either to themselves or to exactly one horizontal, vertical or antidiagonal neighbor 1

%I

%S 5,108,1814,32173,565061,9943416,174911750,3077034244,54130248568,

%T 952245176313,16751640356635,294690365449276,5184113807856060,

%U 91197538858856819,1604322628219475789,28222813114190945744

%N Number of ways to reciprocally link elements of an nX4 array either to themselves or to exactly one horizontal, vertical or antidiagonal neighbor

%C Column 4 of A220553

%H R. H. Hardin, <a href="/A220549/b220549.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 11*a(n-1) +111*a(n-2) +127*a(n-3) -649*a(n-4) -981*a(n-5) +1615*a(n-6) +2067*a(n-7) -2349*a(n-8) -1177*a(n-9) +1383*a(n-10) +199*a(n-11) -337*a(n-12) +3*a(n-13) +31*a(n-14) -a(n-15) -a(n-16)

%e Some solutions for n=3 0=self 2=n 3=ne 4=w 6=e 7=sw 8=s (reciprocal directions total 10)

%e ..6..4..7..8....0..0..6..4....6..4..7..7....8..8..0..7....6..4..7..7

%e ..0..3..0..2....0..7..0..8....0..3..3..0....2..2..3..0....0..3..3..0

%e ..6..4..6..4....3..0..0..2....6..4..0..0....0..0..0..0....6..4..6..4

%K nonn

%O 1,1

%A _R. H. Hardin_ Dec 15 2012

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Last modified August 14 13:43 EDT 2022. Contains 356117 sequences. (Running on oeis4.)