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 A209477 #7 Mar 12 2017 23:34:38 %S A209477 1,3,7,72,866,16660,401634,11891268,413867410,16583242015 %N A209477 Number of n-bead necklaces labeled with numbers -n..n allowing reversal, with sum zero and avoiding the patterns z z+1 z+2 and z z-1 z-2. %C A209477 Diagonal of A209485. %e A209477 Some solutions for n=6: %e A209477 .-6...-3...-6...-6...-6...-6...-6...-4...-6...-6...-6...-6...-2...-6...-6...-5 %e A209477 ..2...-2...-1....0....4....2...-4...-4....2....0...-4....0...-1...-4...-1...-3 %e A209477 ..6....0...-2....0....0....2....5...-2...-2....1....1...-2....1....1....3....0 %e A209477 .-5....0....4...-2...-3....2....0....2....1....0....5...-2...-1....1....3....3 %e A209477 .-2....6....2....3...-1...-4....2....4....0....5....3....5....1....5...-2....6 %e A209477 ..5...-1....3....5....6....4....3....4....5....0....1....5....2....3....3...-1 %K A209477 nonn %O A209477 1,2 %A A209477 _R. H. Hardin_, Mar 09 2012