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 A221434 #8 Feb 20 2025 19:35:36 %S A221434 24,216,576,576,161280,283046400,782137036800,3563924952268800, %T A221434 25315180943034286080,269169718618593283276800, %U A221434 4137679434467601752260608000,89264433387042486497787641856000,2634485866147603716480364478201856000,104038940808800435615474810743389211852800 %N A221434 Number of n X 4 1..(max n,4) arrays with each row and column having unrepeated values. %H A221434 R. H. Hardin, <a href="/A221434/b221434.txt">Table of n, a(n) for n = 1..15</a> %e A221434 Some solutions for n=3: %e A221434 ..2..4..1..3....4..2..3..1....1..3..2..4....4..1..2..3....2..1..3..4 %e A221434 ..3..1..4..2....3..1..4..2....2..4..1..3....1..2..3..4....4..3..2..1 %e A221434 ..4..2..3..1....1..4..2..3....4..2..3..1....3..4..1..2....3..4..1..2 %Y A221434 Column 4 of A221438. %K A221434 nonn %O A221434 1,1 %A A221434 _R. H. Hardin_, Jan 16 2013