cp's OEIS Frontend

A220636 Number of ways to reciprocally link elements of an 6Xn array either to themselves or to exactly two horizontal or antidiagonal neighbors.

%I A220636 #6 Jul 23 2025 01:19:44
%S A220636 1,1,13,351,8560,183961,3817452,79063898,1643423543,34184820039,
%T A220636 711142299027,14793696906106,307746212613995,6401868705356519,
%U A220636 133174202661890384,2770341001987547086,57629691849567578540
%N A220636 Number of ways to reciprocally link elements of an 6Xn array either to themselves or to exactly two horizontal or antidiagonal neighbors.
%C A220636 Row 6 of A220632
%H A220636 R. H. Hardin, <a href="/A220636/b220636.txt">Table of n, a(n) for n = 1..210</a>
%F A220636 Empirical: a(n) = 32*a(n-1) -195*a(n-2) -1350*a(n-3) +10665*a(n-4) +31692*a(n-5) -206199*a(n-6) -507142*a(n-7) +1799954*a(n-8) +4606048*a(n-9) -7358332*a(n-10) -21711948*a(n-11) +13920815*a(n-12) +54513592*a(n-13) -9084809*a(n-14) -73913886*a(n-15) -4653883*a(n-16) +53601160*a(n-17) +7698097*a(n-18) -21029870*a(n-19) -3072503*a(n-20) +4411176*a(n-21) +533603*a(n-22) -476894*a(n-23) -41967*a(n-24) +24240*a(n-25) +1155*a(n-26) -450*a(n-27) for n>32
%e A220636 Some solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10)
%e A220636 .00.67.47...00.67.47...00.67.47...00.00.00...00.00.00...00.00.00...00.67.47
%e A220636 .36.34.00...36.34.00...36.34.00...00.67.47...00.00.00...00.00.00...36.34.00
%e A220636 .00.00.00...00.67.47...00.00.00...36.34.00...00.67.47...00.67.47...00.00.00
%e A220636 .00.00.00...36.34.00...00.00.00...00.00.00...36.34.00...36.34.00...00.67.47
%e A220636 .00.67.47...00.00.00...00.00.00...00.00.00...00.67.47...00.00.00...36.34.00
%e A220636 .36.34.00...00.00.00...00.00.00...00.00.00...36.34.00...00.00.00...00.00.00
%K A220636 nonn
%O A220636 1,3
%A A220636 _R. H. Hardin_ Dec 17 2012