cp's OEIS Frontend

A220601 Number of ways to reciprocally link elements of an nX7 array either to themselves or to exactly two horizontal, vertical and antidiagonal neighbors, without 3-loops.

%I A220601 #6 Jul 23 2025 01:17:18
%S A220601 1,305,190425,60138423,16505365334,4807269151250,1417058414112748,
%T A220601 415538772723268712,121740835171119793585,35681922955520577801844,
%U A220601 10458840906159008629586152,3065510523366853897987776536
%N A220601 Number of ways to reciprocally link elements of an nX7 array either to themselves or to exactly two horizontal, vertical and antidiagonal neighbors, without 3-loops.
%C A220601 Column 7 of A220602
%H A220601 R. H. Hardin, <a href="/A220601/b220601.txt">Table of n, a(n) for n = 1..116</a>
%e A220601 Some solutions for n=3 0=self 2=n 3=ne 4=w 6=e 7=sw 8=s (reciprocal directions total 10)
%e A220601 .00.00.00.00.00.00.78...00.67.48.68.48.00.78...00.78.00.00.67.46.48
%e A220601 .00.00.00.68.46.34.28...36.48.27.28.26.34.27...38.28.00.38.78.78.28
%e A220601 .00.00.00.26.46.46.24...00.23.00.26.46.34.00...26.24.00.23.23.26.24
%K A220601 nonn
%O A220601 1,2
%A A220601 _R. H. Hardin_ Dec 16 2012