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 A209481 #6 Mar 12 2017 23:30:45 %S A209481 1,5,12,72,390,2606,17771,128598,950292,7180767,55056590,427567892, %T A209481 3354737555,26555548849 %N A209481 Number of n-bead necklaces labeled with numbers -4..4 allowing reversal, with sum zero and avoiding the patterns z z+1 z+2 and z z-1 z-2. %C A209481 Column 4 of A209485. %e A209481 Some solutions for n=7: %e A209481 .-3...-4...-3...-4...-3...-4...-4...-3...-2...-4...-4...-3...-2...-4...-3...-1 %e A209481 .-2...-2...-2...-3...-1...-1....1...-1...-2....2....2...-3...-2....2....2...-1 %e A209481 ..4....3....4....0....0....4....1....4...-2...-4....1...-2....1....1...-2...-1 %e A209481 ..0....1....2....4....3...-3...-1...-2....0....3...-2....0...-2...-3....2....0 %e A209481 .-1...-1...-2....2....2....1....1...-1....2...-4....2....3...-1...-2....0....0 %e A209481 ..3...-1....0...-1...-2....2....1...-1....1....3...-2....2....2....3...-1...-1 %e A209481 .-1....4....1....2....1....1....1....4....3....4....3....3....4....3....2....4 %K A209481 nonn %O A209481 1,2 %A A209481 _R. H. Hardin_, Mar 09 2012