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 A224169 #8 Mar 18 2025 20:55:01 %S A224169 130,3526,38561,272130,1460836,6425876,24197608,80350989,240416852, %T A224169 658890738,1675303647,3992383968,8991162356,19265941324,39500748718, %U A224169 77861024489,148143119762,273013479180,488783426991,852309147046,1450785202572,2415419887660,3940248617356 %N A224169 Number of n X 4 0..3 arrays with rows, diagonals and antidiagonals unimodal and columns nondecreasing. %H A224169 R. H. Hardin, <a href="/A224169/b224169.txt">Table of n, a(n) for n = 1..210</a> %F A224169 Empirical: a(n) = (3551/47900160)*n^12 + (17561/13305600)*n^11 + (376693/21772800)*n^10 + (106499/725760)*n^9 + (229093/290304)*n^8 + (4775993/1209600)*n^7 + (239805679/21772800)*n^6 + (2313469/80640)*n^5 + (85217281/1088640)*n^4 - (37150333/907200)*n^3 - (7297121/207900)*n^2 + (474241/1386)*n - 383 for n>3. %e A224169 Some solutions for n=3: %e A224169 ..0..0..1..1....0..1..1..0....3..1..1..0....0..2..1..1....0..2..2..0 %e A224169 ..1..2..2..3....0..3..2..1....3..3..3..3....3..2..2..1....0..3..3..0 %e A224169 ..2..2..2..3....2..3..2..2....3..3..3..3....3..3..3..1....2..3..3..0 %Y A224169 Column 4 of A224173. %K A224169 nonn %O A224169 1,1 %A A224169 _R. H. Hardin_, Mar 31 2013 %E A224169 Name corrected by _Andrew Howroyd_, Mar 18 2025