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 A223978 #6 Jul 23 2025 04:44:51 %S A223978 243,59049,3628696,84988435,1140963027,10676374380,76942621022, %T A223978 453969579904,2284206888340,10088688214569,39954771229458, %U A223978 144202872415543,480339235745630,1491693619175208,4354474074592966 %N A223978 Number of 5Xn 0..2 arrays with rows and antidiagonals unimodal. %C A223978 Row 5 of A223975 %H A223978 R. H. Hardin, <a href="/A223978/b223978.txt">Table of n, a(n) for n = 1..210</a> %F A223978 Empirical: a(n) = (63370093/405483668029440000)*n^20 + (71859847/9357315416064000)*n^19 + (3840596671/12804747411456000)*n^18 + (16093136419/2134124568576000)*n^17 + (89468187533/627683696640000)*n^16 + (124873595783/62768369664000)*n^15 + (2671089252541/125536739328000)*n^14 + (32125296547501/188305108992000)*n^13 + (302581775150461/289700167680000)*n^12 + (44545336450771/9656672256000)*n^11 + (289473882894181/19313344512000)*n^10 + (311624791382747/9656672256000)*n^9 + (1803023416115741/34871316480000)*n^8 + (43416115518617/724250419200)*n^7 + (2936371270324637/47076277248000)*n^6 - (1561630187307499/2615348736000)*n^5 - (2687139777308839/111152321280000)*n^4 - (285271644066077/77189112000)*n^3 + (4647951175288301/586637251200)*n^2 - (79120764337/15519504)*n + 1710 for n>2 %e A223978 Some solutions for n=3 %e A223978 ..0..0..1....0..0..0....0..0..1....0..0..0....0..0..1....0..0..1....0..0..1 %e A223978 ..0..1..1....0..0..2....0..2..0....0..2..0....0..1..0....0..1..2....0..1..0 %e A223978 ..0..0..0....1..2..0....0..1..1....2..2..2....2..1..1....0..1..2....2..1..1 %e A223978 ..0..0..0....0..2..0....1..1..2....2..1..0....2..2..2....0..2..2....2..2..1 %e A223978 ..0..1..0....0..0..1....0..1..1....1..0..0....0..1..1....1..1..1....0..2..1 %K A223978 nonn %O A223978 1,1 %A A223978 _R. H. Hardin_ Mar 30 2013