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 A206251 #7 Jul 22 2025 19:20:55 %S A206251 9409,1718209,49336576,4556324929,226637884225,16533087493120, %T A206251 1006239668280961,68438717405988481,4427204221759169536, %U A206251 295306870252087238017,19431114832514090805121,1289257317404589497597440 %N A206251 Number of (n+1)X5 0..3 arrays with every 2X2 subblock having zero permanent. %C A206251 Column 4 of A206255 %H A206251 R. H. Hardin, <a href="/A206251/b206251.txt">Table of n, a(n) for n = 1..210</a> %F A206251 Empirical: a(n) = 88*a(n-1) -128439*a(n-3) +1879848*a(n-4) +28773144*a(n-5) -593002863*a(n-6) +32230833768*a(n-8) -98419153113*a(n-9) %e A206251 Some solutions for n=4 %e A206251 ..3..3..2..3..0....3..1..1..2..0....0..1..0..2..3....2..1..3..3..1 %e A206251 ..0..0..0..0..0....0..0..0..0..0....0..0..0..0..0....0..0..0..0..0 %e A206251 ..3..0..0..0..3....1..2..1..1..3....0..0..3..2..3....0..1..0..2..2 %e A206251 ..2..0..2..0..3....0..0..0..0..0....1..0..0..0..0....0..1..0..0..0 %e A206251 ..3..0..3..0..0....2..1..1..2..1....0..0..0..1..1....0..1..0..1..3 %K A206251 nonn %O A206251 1,1 %A A206251 _R. H. Hardin_ Feb 05 2012