Triangle by rows T(n,k), showing the number of meanders with length (n+1)*3 and containing (k+1)*3 L's and (n-k)*3 R's, where L's and R's denote arcs of equal length and a central angle of 120 degrees which are positively or negatively oriented.
A194595
Triangle by rows T(n,k), showing the number of meanders with length (n+1)*3 and containing (k+1)*3 L's and (n-k)*3 R's, where L's and R's denote arcs of equal length and a central angle of 120 degrees which are positively or negatively oriented.
Terms
- a(0) =1a(1) =3a(2) =1a(3) =7a(4) =14a(5) =1a(6) =13a(7) =81a(8) =39a(9) =1a(10) =21a(11) =304a(12) =456a(13) =84a(14) =1a(15) =31a(16) =875a(17) =3000a(18) =1750a(19) =155a(20) =1a(21) =43a(22) =2106a(23) =13875a(24) =18500a(25) =5265a(26) =258a(27) =1a(28) =57a(29) =4459
External references
- oeis: A194595