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 A248840 #6 Jul 23 2025 11:47:17 %S A248840 2,6,24,120,720,5040,40318,362804,3626872,39874764,478139586, %T A248840 6209677488,86828161058,1300490408860,20771844841954,352424863147204, %U A248840 6329638315606052,119970031702245396,2393022889885984816 %N A248840 Number of length n arrays x(i), i=1..n with x(i) in 0..i and no value appearing more than 6 times. %C A248840 Column 6 of A248842 %H A248840 R. H. Hardin, <a href="/A248840/b248840.txt">Table of n, a(n) for n = 1..109</a> %e A248840 Some solutions for n=6 %e A248840 ..0....0....0....0....1....1....0....1....0....1....0....0....1....0....0....0 %e A248840 ..1....1....1....1....1....0....0....0....2....0....1....1....1....2....0....1 %e A248840 ..1....1....3....3....0....1....2....3....1....0....1....1....0....0....2....3 %e A248840 ..0....2....2....1....2....0....2....1....0....4....2....1....2....3....3....4 %e A248840 ..1....2....0....2....5....1....5....2....0....1....4....3....0....5....4....1 %e A248840 ..2....0....6....3....2....0....1....4....4....2....6....4....3....5....4....3 %K A248840 nonn %O A248840 1,1 %A A248840 _R. H. Hardin_, Oct 15 2014