This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A251149 #11 Aug 10 2015 17:56:59 %S A251149 13,27,27,53,49,53,107,87,87,107,213,161,143,161,213,427,299,247,247, %T A251149 299,427,853,565,433,401,433,565,853,1707,1075,777,667,667,777,1075, %U A251149 1707,3413,2065,1413,1141,1061,1141,1413,2065,3413,6827,3991,2607,1987,1743 %N A251149 T(n,k) = Number of (n+1) X (k+1) 0..2 arrays with every 2 X 2 subblock summing to 4 and no 2 X 2 subblock having exactly two nonzero entries. %C A251149 Table starts: %C A251149 ...13...27...53...107...213...427...853..1707..3413...6827..13653..27307..54613 %C A251149 ...27...49...87...161...299...565..1075..2065..3991...7761..15163..29749..58563 %C A251149 ...53...87..143...247...433...777..1413..2607..4863...9167..17433..33417..64493 %C A251149 ..107..161..247...401...667..1141..1987..3521..6327..11521..21227..39541..74387 %C A251149 ..213..299..433...667..1061..1743..2925..5003..8689..15307..27317..49359..90237 %C A251149 ..427..565..777..1141..1743..2763..4491..7453.12569..21501..37255..65355.116035 %C A251149 ..853.1075.1413..1987..2925..4491..7101.11491.18917..31587..53389..91275.157789 %C A251149 .1707.2065.2607..3521..5003..7453.11491.18193.29359..48081..79675.133405.225555 %C A251149 .3413.3991.4863..6327..8689.12569.18917.29359.46575..75087.122521.201881.335501 %C A251149 .6827.7761.9167.11521.15307.21501.31587.48081.75087.119441.192507.313341.514067 %H A251149 R. H. Hardin, <a href="/A251149/b251149.txt">Table of n, a(n) for n = 1..364</a> %F A251149 Empirical for column k: %F A251149 k=1: a(n) = a(n-1) +2*a(n-2) %F A251149 k=2: a(n) = 3*a(n-1) -5*a(n-3) +a(n-4) +2*a(n-5) %F A251149 k=3: a(n) = 3*a(n-1) -5*a(n-3) +a(n-4) +2*a(n-5) %F A251149 k=4: a(n) = 3*a(n-1) -5*a(n-3) +a(n-4) +2*a(n-5) %F A251149 k=5: a(n) = 3*a(n-1) -5*a(n-3) +a(n-4) +2*a(n-5) %F A251149 k=6: a(n) = 3*a(n-1) -5*a(n-3) +a(n-4) +2*a(n-5) %F A251149 k=7: a(n) = 3*a(n-1) -5*a(n-3) +a(n-4) +2*a(n-5) %e A251149 Some solutions for n=4, k=4: %e A251149 ..0..1..0..2..1....1..0..1..1..1....1..0..1..1..2....2..1..2..1..1 %e A251149 ..1..2..1..1..0....1..2..1..1..1....1..2..1..1..0....0..1..0..1..1 %e A251149 ..1..0..1..1..2....1..0..1..1..1....0..1..0..2..1....1..2..1..2..0 %e A251149 ..1..2..1..1..0....1..2..1..1..1....1..2..1..1..0....0..1..0..1..1 %e A251149 ..1..0..1..1..2....1..0..1..1..1....0..1..0..2..1....2..1..2..1..1 %Y A251149 Column 1 is A048573(n+2). %K A251149 nonn,tabl %O A251149 1,1 %A A251149 _R. H. Hardin_, Nov 30 2014