cp's OEIS Frontend

A220635 Number of ways to reciprocally link elements of an 5Xn array either to themselves or to exactly two horizontal or antidiagonal neighbors.

%I A220635 #6 Jul 23 2025 01:19:37
%S A220635 1,1,8,114,1481,17527,201903,2329448,26904225,310837917,3591561452,
%T A220635 41499180881,479508472309,5540546671074,64018957168901,
%U A220635 739714921940047,8547125318062702,98758781455779205,1141120102778497151
%N A220635 Number of ways to reciprocally link elements of an 5Xn array either to themselves or to exactly two horizontal or antidiagonal neighbors.
%C A220635 Row 5 of A220632
%H A220635 R. H. Hardin, <a href="/A220635/b220635.txt">Table of n, a(n) for n = 1..210</a>
%F A220635 Empirical: a(n) = 16*a(n-1) -39*a(n-2) -186*a(n-3) +419*a(n-4) +1024*a(n-5) -1049*a(n-6) -2258*a(n-7) +861*a(n-8) +2000*a(n-9) -133*a(n-10) -586*a(n-11) -16*a(n-12) +32*a(n-13) for n>17
%e A220635 Some solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10)
%e A220635 .00.67.47...00.67.47...00.00.00...00.00.00...00.00.00...00.67.47...00.00.00
%e A220635 .36.34.00...36.34.00...00.00.00...00.67.47...00.67.47...36.34.00...00.00.00
%e A220635 .00.67.47...00.00.00...00.00.00...36.34.00...36.34.00...00.00.00...00.00.00
%e A220635 .36.34.00...00.67.47...00.67.47...00.67.47...00.00.00...00.00.00...00.00.00
%e A220635 .00.00.00...36.34.00...36.34.00...36.34.00...00.00.00...00.00.00...00.00.00
%K A220635 nonn
%O A220635 1,3
%A A220635 _R. H. Hardin_ Dec 17 2012