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 A207486 #7 Jul 22 2025 20:29:19 %S A207486 18,324,1014,2749,8808,26980,89417,292136,996484,3383013,11790326, %T A207486 41028862,145231303,513949716,1839937674,6589246547,23788589214, %U A207486 85938464486,312245147469,1135416510570,4145850489950,15151086644931 %N A207486 Number of nX6 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 1 1 and 1 1 0 vertically. %C A207486 Column 6 of A207488 %H A207486 R. H. Hardin, <a href="/A207486/b207486.txt">Table of n, a(n) for n = 1..210</a> %F A207486 Empirical: a(n) = 10*a(n-1) +41*a(n-2) -690*a(n-3) -222*a(n-4) +22096*a(n-5) -21791*a(n-6) -437286*a(n-7) +732922*a(n-8) +6009444*a(n-9) -12701993*a(n-10) -61099848*a(n-11) +147577555*a(n-12) +478142408*a(n-13) -1255150754*a(n-14) -2957438030*a(n-15) +8161114927*a(n-16) +14725379712*a(n-17) -41595538907*a(n-18) -59754024146*a(n-19) +168752909640*a(n-20) +199103609284*a(n-21) -550122341773*a(n-22) -546590772136*a(n-23) +1448863601410*a(n-24) +1235980312350*a(n-25) -3090533100043*a(n-26) -2294534240580*a(n-27) +5339956050711*a(n-28) +3476856379768*a(n-29) -7459679337302*a(n-30) -4266468793724*a(n-31) +8393037191294*a(n-32) +4198996432596*a(n-33) -7561119429642*a(n-34) -3276898001616*a(n-35) +5409499480172*a(n-36) +2000740096692*a(n-37) -3039700576604*a(n-38) -940441955640*a(n-39) +1321948665560*a(n-40) +333540162360*a(n-41) -436247928624*a(n-42) -86906616880*a(n-43) +106304956896*a(n-44) +16010723008*a(n-45) -18384237312*a(n-46) -1961992960*a(n-47) +2118560256*a(n-48) +142748672*a(n-49) -144900096*a(n-50) -4644864*a(n-51) +4423680*a(n-52) for n>53 %e A207486 Some solutions for n=4 %e A207486 ..1..0..1..0..0..1....1..1..1..0..1..0....0..0..1..0..0..1....0..0..1..0..1..0 %e A207486 ..1..1..1..1..0..0....1..1..0..0..1..0....0..0..1..0..0..1....0..0..1..0..0..1 %e A207486 ..1..0..1..0..1..0....1..1..1..1..1..1....1..1..1..0..0..1....1..0..1..0..1..0 %e A207486 ..1..0..1..0..0..1....1..1..0..0..1..0....0..0..1..0..0..1....0..0..1..0..0..1 %K A207486 nonn %O A207486 1,1 %A A207486 _R. H. Hardin_ Feb 18 2012