A220722 - OEIS

%I #4 Dec 18 2012 09:41:30

%S 1,68,1819,52189,1485872,42378036,1208447287,34459871148,982649830527,

%T 28021037742705,799042082604660,22785317589182003,649741368852004381,

%U 18527889499243277120,528337436670523419632,15065960264863439367995

%N Number of ways to reciprocally link elements of an nX5 array either to themselves or to exactly two horizontal, diagonal or antidiagonal neighbors

%C Column 5 of A220725

%H R. H. Hardin, <a href="/A220722/b220722.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 24*a(n-1) +104*a(n-2) +571*a(n-3) +3582*a(n-4) +7794*a(n-5) +4788*a(n-6) -16926*a(n-7) -90288*a(n-8) -168845*a(n-9) -84443*a(n-10) +109179*a(n-11) +193126*a(n-12) +248993*a(n-13) +425415*a(n-14) +384428*a(n-15) +353459*a(n-16) +31964*a(n-17) -136170*a(n-18) -85703*a(n-19) -29195*a(n-20) +14155*a(n-21) +6903*a(n-22) +243*a(n-23) -252*a(n-24) -25*a(n-25)

%e Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)

%e .69.47.69.46.47...69.47.00.69.47...00.69.46.46.47...00.69.46.49.00

%e .39.19.00.13.00...39.16.47.36.14...00.69.14.37.00...00.00.16.46.14

%e .00.16.14.00.00...00.13.00.00.00...00.00.13.00.00...00.00.00.00.00

%K nonn

%O 1,2

%A _R. H. Hardin_ Dec 18 2012