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 A208161 #7 Jul 22 2025 21:12:24 %S A208161 13,169,699,2920,14446,63031,258952,1088966,4519672,18366772,74473407, %T A208161 301250239,1211354604,4857059037,19448559879,77732455665,310249629843, %U A208161 1237296397590,4930959447666,19639536330789,78190784495920 %N A208161 Number of nX5 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 0 1 0 vertically. %C A208161 Column 5 of A208164 %H A208161 R. H. Hardin, <a href="/A208161/b208161.txt">Table of n, a(n) for n = 1..210</a> %F A208161 Empirical: a(n) = 3*a(n-1) +55*a(n-3) -76*a(n-4) -116*a(n-5) -1244*a(n-6) +20*a(n-7) +2433*a(n-8) +16145*a(n-9) +14430*a(n-10) -13054*a(n-11) -127390*a(n-12) -184144*a(n-13) -41832*a(n-14) +600995*a(n-15) +1155989*a(n-16) +795403*a(n-17) -1628302*a(n-18) -4310878*a(n-19) -4192301*a(n-20) +2041886*a(n-21) +10103799*a(n-22) +12201828*a(n-23) +1213903*a(n-24) -15008727*a(n-25) -22149805*a(n-26) -8930474*a(n-27) +13538545*a(n-28) +26058738*a(n-29) +15415978*a(n-30) -6255866*a(n-31) -19998071*a(n-32) -14466661*a(n-33) +135702*a(n-34) +10021550*a(n-35) +8139334*a(n-36) +1168211*a(n-37) -3502825*a(n-38) -2851295*a(n-39) -326881*a(n-40) +1142010*a(n-41) +755296*a(n-42) -54940*a(n-43) -410599*a(n-44) -234916*a(n-45) +7373*a(n-46) +100275*a(n-47) +65371*a(n-48) +14560*a(n-49) -7778*a(n-50) -7888*a(n-51) -3096*a(n-52) -672*a(n-53) %e A208161 Some solutions for n=4 %e A208161 ..0..0..1..0..0....0..1..1..1..0....0..0..1..1..1....1..0..0..1..1 %e A208161 ..1..0..0..1..1....1..1..1..0..0....1..1..1..1..1....0..1..0..0..1 %e A208161 ..1..0..0..1..1....1..0..0..1..0....1..1..0..0..1....1..1..0..0..1 %e A208161 ..1..0..0..1..1....0..1..1..1..0....0..1..1..0..0....1..1..0..0..1 %K A208161 nonn %O A208161 1,1 %A A208161 _R. H. Hardin_ Feb 24 2012