cp's OEIS Frontend

A220711 Number of ways to reciprocally link elements of an 6Xn array either to themselves or to exactly two horizontal and antidiagonal neighbors, without consecutive collinear links.

%I A220711 #6 Jul 23 2025 01:22:32
%S A220711 1,1,13,60,317,1617,8338,42873,221082,1139020,5870960,30259204,
%T A220711 155962396,803874071,4143371101,21356146495,110075467413,567360680620,
%U A220711 2924337273221,15072870834560,77689863937436,400435729023800
%N A220711 Number of ways to reciprocally link elements of an 6Xn array either to themselves or to exactly two horizontal and antidiagonal neighbors, without consecutive collinear links.
%C A220711 Row 6 of A220708
%H A220711 R. H. Hardin, <a href="/A220711/b220711.txt">Table of n, a(n) for n = 1..210</a>
%F A220711 Empirical: a(n) = a(n-1) +33*a(n-2) -a(n-3) -351*a(n-4) -75*a(n-5) +1760*a(n-6) +436*a(n-7) -4708*a(n-8) -997*a(n-9) +6997*a(n-10) +1085*a(n-11) -5748*a(n-12) -564*a(n-13) +2512*a(n-14) +131*a(n-15) -543*a(n-16) -7*a(n-17) +49*a(n-18) -a(n-19) -a(n-20) for n>24
%e A220711 Some solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10)
%e A220711 .00.67.47...00.00.00...00.00.00...00.00.00...00.67.47...00.00.00...00.00.00
%e A220711 .36.34.00...00.67.47...00.00.00...00.00.00...36.34.00...00.67.47...00.00.00
%e A220711 .00.00.00...36.34.00...00.00.00...00.00.00...00.67.47...36.34.00...00.67.47
%e A220711 .00.67.47...00.67.47...00.00.00...00.00.00...36.34.00...00.00.00...36.34.00
%e A220711 .36.34.00...36.34.00...00.00.00...00.67.47...00.00.00...00.00.00...00.00.00
%e A220711 .00.00.00...00.00.00...00.00.00...36.34.00...00.00.00...00.00.00...00.00.00
%K A220711 nonn
%O A220711 1,3
%A A220711 _R. H. Hardin_ Dec 18 2012