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 A223807 #7 Jul 23 2025 04:32:50 %S A223807 50,2500,58806,825896,8165133,62305953,388531932,2057610878, %T A223807 9513089522,39201336756,146317003838,501049337826,1590725248238, %U A223807 4722687426852,13206968194237,35002231000213,88376951307032,213545507535686 %N A223807 Number of nX3 0..3 arrays with rows, columns, diagonals and antidiagonals unimodal. %C A223807 Column 3 of A223811 %H A223807 R. H. Hardin, <a href="/A223807/b223807.txt">Table of n, a(n) for n = 1..210</a> %F A223807 Empirical: a(n) = (89/169374965760)*n^18 + (838301/44460928512000)*n^17 + (131561/298896998400)*n^16 + (2899703/435891456000)*n^15 + (20728921/261534873600)*n^14 + (44295233/62270208000)*n^13 + (61053571/11496038400)*n^12 + (1555111843/50295168000)*n^11 + (157620907/1045094400)*n^10 + (3423292861/6096384000)*n^9 + (56948336183/32188907520)*n^8 + (18757539769/4790016000)*n^7 + (288950150603/37362124800)*n^6 + (2420059673699/326918592000)*n^5 + (12916777153/889574400)*n^4 + (2892057797/4540536000)*n^3 + (22972148831/1029188160)*n^2 - (1109957/29172)*n + 29 %e A223807 Some solutions for n=3 %e A223807 ..2..2..1....0..3..3....0..3..3....1..2..0....0..0..0....0..0..1....2..0..0 %e A223807 ..3..3..1....2..3..3....1..1..3....1..2..0....0..3..3....1..3..3....2..2..3 %e A223807 ..0..2..1....3..3..0....0..1..2....3..2..0....1..3..3....1..2..2....2..3..3 %K A223807 nonn %O A223807 1,1 %A A223807 _R. H. Hardin_ Mar 27 2013