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 A185517 #7 Jul 22 2025 09:51:45 %S A185517 10847,1058503,35659489,2183297449,96865190255,5157904182519, %T A185517 249246507105681,12721664424927033,630667351622299519, %U A185517 31779395697846344999,1587432658714531328833,79681759021406117870025 %N A185517 Number of (n+1)X6 0..2 arrays with every 2X2 subblock singular. %C A185517 Column 5 of A185521 %H A185517 R. H. Hardin, <a href="/A185517/b185517.txt">Table of n, a(n) for n = 1..124</a> %F A185517 Empirical: a(n)=124*a(n-1)-4828*a(n-2)+9640*a(n-3)+4211198*a(n-4)-108674648*a(n-5)+428321452*a(n-6)+23596172360*a(n-7)-388971416381*a(n-8)+572244355004*a(n-9)+40557598916624*a(n-10)-386088931978704*a(n-11)+8157694824096*a(n-12)+19937500201681088*a(n-13)-107256141951991808*a(n-14)-112420856782623488*a(n-15)+3046625671768687360*a(n-16)-9264406533882734592*a(n-17)-12424668477383446528*a(n-18)+137806999333441568768*a(n-19)-276536454577537679360*a(n-20)-125316061156482220032*a(n-21)+1408091287365347180544*a(n-22)-2387876314993964089344*a(n-23)+1658731722007080075264*a(n-24)-273671360333161168896*a(n-25)-124425274583131619328*a(n-26) %e A185517 Some solutions for 3X6 %e A185517 ..0..0..0..0..0..0....0..0..1..2..1..1....1..0..0..0..2..1....0..0..2..1..0..2 %e A185517 ..0..2..0..0..0..2....0..0..0..0..0..0....0..0..0..0..0..0....0..0..0..0..0..1 %e A185517 ..0..0..0..2..0..2....0..1..0..1..1..1....0..1..1..1..1..2....0..1..0..2..0..0 %K A185517 nonn %O A185517 1,1 %A A185517 _R. H. Hardin_ Jan 29 2011