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 A274732 #4 Jul 03 2016 20:21:24 %S A274732 32,1296,16524,301784,5634776,105328812,1980677448,37188898120, %T A274732 699226867860,13139454740876,246989200003420,4642070954166124, %U A274732 87252983103535936,1639953977382243676,30824192792654598004 %N A274732 Number of 7Xn 0..2 arrays with no element equal to any value at offset (-1,-2) (-2,-1) or (-1,0) and new values introduced in order 0..2. %C A274732 Row 7 of A274728. %H A274732 R. H. Hardin, <a href="/A274732/b274732.txt">Table of n, a(n) for n = 1..210</a> %F A274732 Empirical: a(n) = 21*a(n-1) +46*a(n-2) -2078*a(n-3) +7099*a(n-4) +30390*a(n-5) -199330*a(n-6) +32493*a(n-7) +1799239*a(n-8) -2883655*a(n-9) -6458651*a(n-10) +19972172*a(n-11) +4488011*a(n-12) -63185111*a(n-13) +38593516*a(n-14) +97573203*a(n-15) -147528893*a(n-16) +26937123*a(n-17) +105357461*a(n-18) -172813699*a(n-19) +142443589*a(n-20) +18232365*a(n-21) -135277945*a(n-22) +91577781*a(n-23) -13939351*a(n-24) -6667960*a(n-25) +1422372*a(n-26) +709307*a(n-27) -229702*a(n-28) +8892*a(n-29) +1296*a(n-30) for n>34 %e A274732 Some solutions for n=3 %e A274732 ..0..1..0. .0..1..0. .0..1..0. .0..0..0. .0..1..0. .0..1..0. .0..0..0 %e A274732 ..2..0..1. .1..2..1. .2..0..2. .1..2..1. .1..2..2. .1..0..2. .1..2..1 %e A274732 ..0..1..0. .2..1..2. .1..1..0. .0..1..2. .0..1..0. .0..2..0. .2..1..2 %e A274732 ..2..0..2. .1..0..0. .2..0..2. .2..0..1. .2..0..1. .1..0..1. .1..2..0 %e A274732 ..0..2..0. .2..1..2. .0..2..0. .0..1..0. .0..1..0. .2..1..0. .2..1..2 %e A274732 ..2..0..1. .0..0..1. .2..0..2. .1..0..2. .2..0..2. .0..2..1. .1..2..1 %e A274732 ..1..1..0. .1..1..2. .1..1..0. .0..2..0. .1..2..0. .2..0..2. .0..1..0 %Y A274732 Cf. A274728. %K A274732 nonn %O A274732 1,1 %A A274732 _R. H. Hardin_, Jul 03 2016