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 A267731 #4 Jan 20 2016 07:04:28 %S A267731 15,225,3375,39330,451278,4705642,47293550,453985015,4225323881, %T A267731 38217977443,337785304853,2925589051944,24901832826668, %U A267731 208741721350212,1726400790939232,14108352548185285,114068503433280219 %N A267731 Number of nX4 0..1 arrays with every repeated value in every row and column greater than or equal to the previous repeated value. %C A267731 Column 4 of A267735. %H A267731 R. H. Hardin, <a href="/A267731/b267731.txt">Table of n, a(n) for n = 1..210</a> %F A267731 Empirical: a(n) = 35*a(n-1) -394*a(n-2) +232*a(n-3) +25654*a(n-4) -115936*a(n-5) -717645*a(n-6) +5125019*a(n-7) +12766457*a(n-8) -121244771*a(n-9) -191484356*a(n-10) +1834417718*a(n-11) +2792153531*a(n-12) -18018352091*a(n-13) -33384924485*a(n-14) +106494035885*a(n-15) +256764018305*a(n-16) -325748093657*a(n-17) -1087241545583*a(n-18) +521256387815*a(n-19) +2786626662683*a(n-20) -415177386323*a(n-21) -4689075652721*a(n-22) +179629691969*a(n-23) +5392367300186*a(n-24) -290951802380*a(n-25) -4225877115281*a(n-26) +592280920475*a(n-27) +2150396673689*a(n-28) -541241558807*a(n-29) -652332203444*a(n-30) +234631819886*a(n-31) +111137103164*a(n-32) -54396401114*a(n-33) -9115774331*a(n-34) +7011916217*a(n-35) +58342140*a(n-36) -479433676*a(n-37) +42704816*a(n-38) +14044864*a(n-39) -2279168*a(n-40) -40960*a(n-41) +16384*a(n-42) %e A267731 Some solutions for n=4 %e A267731 ..1..1..0..1....1..0..0..1....0..0..1..1....1..1..1..0....0..1..0..1 %e A267731 ..0..1..1..1....0..0..0..0....0..1..0..0....0..1..0..0....0..1..1..0 %e A267731 ..0..0..0..1....0..0..1..1....1..0..1..1....1..0..0..0....1..1..1..1 %e A267731 ..1..1..1..0....0..0..1..1....1..1..1..0....0..1..1..0....0..0..0..0 %Y A267731 Cf. A267735. %K A267731 nonn %O A267731 1,1 %A A267731 _R. H. Hardin_, Jan 20 2016