cp's OEIS Frontend

A268740 T(n,k)=Number of nXk binary arrays with some 1 horizontally or vertically adjacent to some other 1 exactly once.

%I A268740 #4 Feb 12 2016 08:47:01
%S A268740 0,1,1,2,4,2,5,15,15,5,10,48,80,48,10,20,145,396,396,145,20,38,420,
%T A268740 1788,2876,1788,420,38,71,1183,7831,19591,19591,7831,1183,71,130,3264,
%U A268740 33170,128232,200204,128232,33170,3264,130,235,8865,137868,816009,1971414
%N A268740 T(n,k)=Number of nXk binary arrays with some 1 horizontally or vertically adjacent to some other 1 exactly once.
%C A268740 Table starts
%C A268740 ...0.....1.......2.........5..........10............20.............38
%C A268740 ...1.....4......15........48.........145...........420...........1183
%C A268740 ...2....15......80.......396........1788..........7831..........33170
%C A268740 ...5....48.....396......2876.......19591........128232.........816009
%C A268740 ..10...145....1788.....19591......200204.......1971414.......18847982
%C A268740 ..20...420....7831....128232.....1971414......29134076......418632185
%C A268740 ..38..1183...33170....816009....18847982.....418632185.....9039552112
%C A268740 ..71..3264..137868...5087814...176668038....5894815754...191307160577
%C A268740 .130..8865..563486..31228804..1629738420...81718671716..3985770068310
%C A268740 .235.23780.2275119.189328186.14851460143.1119014223138.82030747371058
%H A268740 R. H. Hardin, <a href="/A268740/b268740.txt">Table of n, a(n) for n = 1..1404</a>
%F A268740 Empirical for column k:
%F A268740 k=1: a(n) = 2*a(n-1) +a(n-2) -2*a(n-3) -a(n-4)
%F A268740 k=2: a(n) = 4*a(n-1) -2*a(n-2) -4*a(n-3) -a(n-4)
%F A268740 k=3: a(n) = 4*a(n-1) +8*a(n-2) -24*a(n-3) -38*a(n-4) +4*a(n-5) +12*a(n-6) -a(n-8)
%F A268740 k=4: [order 10]
%F A268740 k=5: [order 18]
%F A268740 k=6: [order 22]
%F A268740 k=7: [order 42]
%e A268740 Some solutions for n=4 k=4
%e A268740 ..0..1..0..1. .0..0..0..1. .0..1..0..1. .0..0..1..0. .0..1..0..0
%e A268740 ..1..0..0..0. .1..0..0..0. .0..0..0..1. .1..1..0..0. .1..0..0..1
%e A268740 ..0..1..0..1. .0..1..1..0. .0..0..0..0. .0..0..1..0. .0..1..1..0
%e A268740 ..0..0..0..1. .1..0..0..0. .1..0..1..0. .0..0..0..0. .1..0..0..0
%Y A268740 Column 1 is A001629.
%Y A268740 Column 2 is A093967.
%K A268740 nonn,tabl
%O A268740 1,4
%A A268740 _R. H. Hardin_, Feb 12 2016