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 A248838 #6 Jul 23 2025 11:47:04 %S A248838 2,6,24,120,718,4994,39556,351320,3456742,37314126,438366374, %T A248838 5567209930,75995663398,1109556555434,17252609166736,284620418911180, %U A248838 4965138989585412,91317809653363376,1765937111915469414 %N A248838 Number of length n arrays x(i), i=1..n with x(i) in 0..i and no value appearing more than 4 times. %C A248838 Column 4 of A248842 %H A248838 R. H. Hardin, <a href="/A248838/b248838.txt">Table of n, a(n) for n = 1..196</a> %e A248838 Some solutions for n=6 %e A248838 ..0....1....1....1....0....0....1....0....0....1....0....1....1....0....1....1 %e A248838 ..0....2....2....0....0....2....0....2....2....0....2....1....1....2....0....1 %e A248838 ..3....2....2....0....2....2....3....2....0....3....1....0....2....2....1....3 %e A248838 ..3....0....3....3....3....2....1....2....0....0....0....4....0....1....0....0 %e A248838 ..0....5....0....2....2....1....2....2....4....3....2....0....5....4....1....1 %e A248838 ..3....4....5....1....6....5....5....5....6....2....1....1....5....4....0....2 %K A248838 nonn %O A248838 1,1 %A A248838 _R. H. Hardin_, Oct 15 2014