cp's OEIS Frontend

A183328 T(n,k)=Number of nXk binary arrays with each 1 adjacent to exactly two other 1s.

%I A183328 #7 Jul 22 2025 08:49:46
%S A183328 1,1,1,1,2,1,1,3,3,1,1,4,6,4,1,1,6,10,10,6,1,1,9,19,27,19,9,1,1,13,37,
%T A183328 72,72,37,13,1,1,19,69,179,289,179,69,19,1,1,28,129,447,996,996,447,
%U A183328 129,28,1,1,41,244,1139,3325,4740,3325,1139,244,41,1,1,60,460,2912,11415,21259
%N A183328 T(n,k)=Number of nXk binary arrays with each 1 adjacent to exactly two other 1s.
%C A183328 Table starts
%C A183328 .1..1...1....1......1.......1........1.........1..........1...........1
%C A183328 .1..2...3....4......6.......9.......13........19.........28..........41
%C A183328 .1..3...6...10.....19......37.......69.......129........244.........460
%C A183328 .1..4..10...27.....72.....179......447......1139.......2912........7434
%C A183328 .1..6..19...72....289.....996.....3325.....11415......39720......138689
%C A183328 .1..9..37..179....996....4740....21259.....96524.....443793.....2054180
%C A183328 .1.13..69..447...3325...21259...128371....770542....4639132....28160294
%C A183328 .1.19.129.1139..11415...96524...770542...6115158...48449560...386449543
%C A183328 .1.28.244.2912..39720..443793..4639132..48449560..505971397..5319953708
%C A183328 .1.41.460.7434.138689.2054180.28160294.386449543.5319953708.73890230419
%H A183328 R. H. Hardin, <a href="/A183328/b183328.txt">Table of n, a(n) for n = 1..391</a>
%e A183328 Some solutions for 7X6
%e A183328 ..0..1..1..1..1..1....0..0..1..1..1..0....0..0..1..1..1..1....0..0..1..1..1..0
%e A183328 ..0..1..0..0..0..1....0..1..1..0..1..0....1..1..1..0..0..1....0..0..1..0..1..0
%e A183328 ..0..1..0..1..1..1....1..1..0..0..1..1....1..0..0..0..0..1....1..1..1..0..1..1
%e A183328 ..0..1..0..1..0..0....1..0..0..0..0..1....1..1..0..0..0..1....1..0..0..0..0..1
%e A183328 ..1..1..0..1..1..0....1..0..0..0..1..1....0..1..0..0..0..1....1..1..0..0..0..1
%e A183328 ..1..0..0..0..1..0....1..0..1..1..1..0....0..1..1..1..0..1....0..1..1..0..0..1
%e A183328 ..1..1..1..1..1..0....1..1..1..0..0..0....0..0..0..1..1..1....0..0..1..1..1..1
%Y A183328 Column 2 is A000930(n+1)
%K A183328 nonn,tabl
%O A183328 1,5
%A A183328 _R. H. Hardin_ Jan 03 2011