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 A207906 #7 Jul 22 2025 20:58:11 %S A207906 25,625,3969,19881,87025,314721,1113025,3674889,11758041,37222201, %T A207906 115369081,356794321,1097663161,3366900625,10334958921,31687204081, %U A207906 97226099721,298466635041,916505619649,2816291468761,8656864485025 %N A207906 Number of nX6 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 0 and 0 1 1 vertically. %C A207906 Column 6 of A207908 %H A207906 R. H. Hardin, <a href="/A207906/b207906.txt">Table of n, a(n) for n = 1..210</a> %F A207906 Empirical: a(n) = 9*a(n-1) -25*a(n-2) +10*a(n-3) +11*a(n-4) +234*a(n-5) -668*a(n-6) +479*a(n-7) -245*a(n-8) +1805*a(n-9) -4260*a(n-10) +6003*a(n-11) -6488*a(n-12) +6128*a(n-13) -13265*a(n-14) +27257*a(n-15) -29449*a(n-16) +24594*a(n-17) -32021*a(n-18) +49194*a(n-19) -67268*a(n-20) +69023*a(n-21) -55533*a(n-22) +60189*a(n-23) -80428*a(n-24) +89339*a(n-25) -79328*a(n-26) +60128*a(n-27) -55387*a(n-28) +62435*a(n-29) -60147*a(n-30) +47086*a(n-31) -31095*a(n-32) +23230*a(n-33) -23140*a(n-34) +20037*a(n-35) -13527*a(n-36) +7247*a(n-37) -3820*a(n-38) +3473*a(n-39) -3016*a(n-40) +1776*a(n-41) -659*a(n-42) +91*a(n-43) -107*a(n-44) +182*a(n-45) -127*a(n-46) +46*a(n-47) +4*a(n-48) -3*a(n-49) -7*a(n-50) +7*a(n-51) -4*a(n-52) +a(n-53) %e A207906 Some solutions for n=4 %e A207906 ..1..1..0..1..1..1....0..1..1..1..0..0....1..0..1..1..1..0....1..0..1..1..1..1 %e A207906 ..0..0..1..1..0..0....1..0..1..1..1..0....0..1..1..1..1..0....0..0..1..1..0..0 %e A207906 ..1..1..0..1..1..1....0..1..1..0..0..1....0..0..1..1..0..1....1..1..1..0..1..1 %e A207906 ..0..0..1..1..0..0....1..0..1..1..0..0....1..0..1..1..1..0....0..0..1..1..0..0 %K A207906 nonn %O A207906 1,1 %A A207906 _R. H. Hardin_ Feb 21 2012