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 A298089 #4 Jan 12 2018 09:30:11 %S A298089 2,13,19,30,53,92,149,250,426,809,1456,2602,4606,8096,14731,27112, %T A298089 49118,88604,159685,288458,526293,960108,1742179,3159153,5731030, %U A298089 10414879,18970871,34518779,62715041,113954032,207132787,376765957,685570021 %N A298089 Number of nX4 0..1 arrays with every element equal to 1, 2, 4 or 7 king-move adjacent elements, with upper left element zero. %C A298089 Column 4 of A298093. %H A298089 R. H. Hardin, <a href="/A298089/b298089.txt">Table of n, a(n) for n = 1..210</a> %F A298089 Empirical: a(n) = 2*a(n-1) +a(n-2) -a(n-3) -2*a(n-4) +2*a(n-5) +4*a(n-6) -28*a(n-7) -3*a(n-8) +26*a(n-9) +22*a(n-10) +6*a(n-11) +7*a(n-12) +53*a(n-13) -42*a(n-14) -84*a(n-15) -64*a(n-16) -24*a(n-17) -3*a(n-18) +40*a(n-19) +101*a(n-20) +36*a(n-21) +51*a(n-22) +23*a(n-23) +75*a(n-24) -85*a(n-25) -129*a(n-26) +23*a(n-27) +6*a(n-28) -58*a(n-29) -108*a(n-30) +41*a(n-31) +87*a(n-32) +38*a(n-33) -2*a(n-34) -10*a(n-35) for n>40 %e A298089 Some solutions for n=7 %e A298089 ..0..0..1..1. .0..1..0..1. .0..0..1..1. .0..0..1..0. .0..0..1..0 %e A298089 ..1..1..0..0. .1..0..1..1. .1..0..1..0. .1..1..0..1. .1..1..0..1 %e A298089 ..0..0..0..1. .0..1..0..0. .1..1..1..0. .0..0..0..1. .1..0..1..0 %e A298089 ..1..1..0..1. .0..1..1..1. .1..1..1..0. .1..0..1..0. .1..1..1..0 %e A298089 ..0..0..1..0. .1..0..1..0. .1..0..1..0. .0..1..1..1. .1..1..1..0 %e A298089 ..0..1..0..1. .0..0..0..1. .1..1..0..1. .0..1..0..0. .1..0..1..0 %e A298089 ..0..0..0..1. .1..1..0..1. .0..0..1..0. .1..0..1..1. .0..0..1..1 %Y A298089 Cf. A298093. %K A298089 nonn %O A298089 1,1 %A A298089 _R. H. Hardin_, Jan 12 2018