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 A209336 #7 Mar 12 2017 23:51:21 %S A209336 1,3,7,72,883,16968,409199,12099880,420661470,16838275108,762821788869 %N A209336 Number of n-bead necklaces labeled with numbers -n..n allowing reversal, with sum zero with no three beads in a row equal. %C A209336 Diagonal of A209344. %e A209336 Some solutions for n=6: %e A209336 .-4...-5...-6...-4...-6...-5...-5...-5...-5...-5...-3...-5...-5...-6...-6...-5 %e A209336 .-3...-4....5....2...-4....3....3....0...-4....0...-2...-3....1...-3....0....0 %e A209336 ..6....5...-4....3....6...-3...-1....2...-4...-3...-1....1....2....2....3....0 %e A209336 ..0....0...-5...-3....3....0...-3...-2....6....3....0...-2...-4....1....3...-1 %e A209336 ..0....2....4...-1....1....1....2...-1....4....0....5....5....0....0...-4....1 %e A209336 ..1....2....6....3....0....4....4....6....3....5....1....4....6....6....4....5 %K A209336 nonn %O A209336 1,2 %A A209336 _R. H. Hardin_, Mar 06 2012