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 A224025 #8 Aug 26 2018 09:50:44 %S A224025 64,1000,6796,32523,122523,387729,1074167,2679260,6137666,13104218, %T A224025 26368076,50439449,92358199,162782299,277423483,458907498,739147146, %U A224025 1162327788,1788617172,2698724343,3999445995,5830352933,8371784327 %N A224025 Number of 3 X n 0..3 arrays with rows nondecreasing and antidiagonals unimodal. %C A224025 Row 3 of A224024. %H A224025 R. H. Hardin, <a href="/A224025/b224025.txt">Table of n, a(n) for n = 1..210</a> %F A224025 Empirical: a(n) = (353/181440)*n^9 + (5/126)*n^8 + (12287/30240)*n^7 + (131/60)*n^6 + (64877/8640)*n^5 + (135/8)*n^4 + (998257/45360)*n^3 + (53933/2520)*n^2 + (3421/252)*n - 2 for n>1. %F A224025 Conjectures from _Colin Barker_, Aug 26 2018: (Start) %F A224025 G.f.: x*(64 + 360*x - 324*x^2 + 1883*x^3 - 3447*x^4 + 4386*x^5 - 3748*x^6 + 2193*x^7 - 825*x^8 + 182*x^9 - 18*x^10) / (1 - x)^10. %F A224025 a(n) = 10*a(n-1) - 45*a(n-2) + 120*a(n-3) - 210*a(n-4) + 252*a(n-5) - 210*a(n-6) + 120*a(n-7) - 45*a(n-8) + 10*a(n-9) - a(n-10) for n>11. %F A224025 (End) %e A224025 Some solutions for n=3: %e A224025 ..2..2..2....1..2..3....0..0..1....2..3..3....1..1..3....3..3..3....2..2..2 %e A224025 ..1..2..2....3..3..3....1..1..3....1..1..1....2..2..2....1..1..2....2..3..3 %e A224025 ..3..3..3....0..2..2....2..2..2....1..1..3....0..0..0....1..1..2....0..1..1 %Y A224025 Cf. A224024. %K A224025 nonn %O A224025 1,1 %A A224025 _R. H. Hardin_, Mar 30 2013