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 A224393 #6 Jul 23 2025 05:09:08 %S A224393 256,10000,86701,497958,2332222,9331553,32806574,103452812,297410156, %T A224393 789731500,1957606141,4569537752,10116846904,21372349639,43300242010, %U A224393 84493906854,159387825448,291579791772,518714491591,899524090772 %N A224393 Number of 4Xn 0..3 arrays with diagonals and antidiagonals unimodal and rows nondecreasing. %C A224393 Row 4 of A224391 %H A224393 R. H. Hardin, <a href="/A224393/b224393.txt">Table of n, a(n) for n = 1..210</a> %F A224393 Empirical: a(n) = (3551/47900160)*n^12 + (17561/13305600)*n^11 + (410317/21772800)*n^10 + (127787/725760)*n^9 + (394837/290304)*n^8 + (4724393/1209600)*n^7 + (880093831/21772800)*n^6 - (673403/80640)*n^5 + (476636641/1088640)*n^4 + (58121267/907200)*n^3 - (1924453/415800)*n^2 - (1998055/2772)*n + 1906 for n>4 %e A224393 Some solutions for n=3 %e A224393 ..0..0..1....0..1..2....3..3..3....0..3..3....0..0..3....2..2..2....1..1..3 %e A224393 ..0..2..3....0..3..3....0..1..3....2..3..3....0..1..1....2..3..3....3..3..3 %e A224393 ..2..2..2....2..3..3....0..0..1....2..3..3....1..1..2....0..2..3....1..3..3 %e A224393 ..1..2..3....0..2..3....0..1..2....2..2..3....0..0..2....2..3..3....0..1..1 %K A224393 nonn %O A224393 1,1 %A A224393 _R. H. Hardin_ Apr 05 2013