The OEIS is supported by the many generous donors to the OEIS Foundation.


(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A207851 Number of meanders of order 2n+1 (4*n+2 crossings of the infinite line) with only central 1-1 cut (no other 1-1 cuts). 2
4, 16, 324, 12100, 595984, 35236096, 2363709924, 174221090404, 13815880848784, 1161868621405636, 102544273501721104, 9424551852935116804, 896612457556434503824, 87881363502264179831824, 8840846163309028336017124 (list; graph; refs; listen; history; text; internal format)
Central cut is a 1-1 cut at the center of the meander (the i-line is for i=n).
A. Panayotopoulos and P. Tsikouras, Properties of meanders, JCMCC 46 (2003), 181-190.
A. Panayotopoulos and P. Vlamos, Meandric Polygons, Ars Combinatoria 87 (2008), 147-159.
Iwan Jensen, Enumeration of plane meanders, arXiv:cond-mat/9910313 [cond-mat.stat-mech], 1999.
S. K. Lando and A. K. Zvonkin, Plane and projective meanders, Theoretical Computer Science Vol. 117, pp. 227-241, 1993.
A. Panayotopoulos and P. Tsikouras, The multimatching property of nested sets, Math. & Sci. Hum. 149 (2000), 23-30.
A. Panayotopoulos and P. Tsikouras, Meanders and Motzkin Words, J. Integer Seqs., Vol. 7, 2004.
A. Panayotopoulos and P. Vlamos, Cutting Degree of Meanders, Artificial Intelligence Applications and Innovations, IFIP Advances in Information and Communication Technology, Volume 382, 2012, pp 480-489; DOI 10.1007/978-3-642-33412-2_49. - From N. J. A. Sloane, Dec 29 2012
(C/C++) int a(int n){
return w2(i)^2;
int w1(int order, int i){
if (i%2==0) error("error in w1(%d, %d), i is even\n", order, i);
if (order%2) error("error in w1(%d, %d), order is odd\n", order, i);
return w2(i+1)*w(order-i+1);
int w2(int order){
if (order%2) error("error in w2(%d), order is odd\n", order);
return w(order)-w3(order);
int w3(int order){
if (order%2) error("error in w3(%d), order is odd\n", order);
int sum=0;
int i;
for (i=3; i<=order-3; i+=2)
sum+=w1(order, i);
return sum;
// w(int i), no source here, is the respective meandric number according to Jensen A005315
Sequence in context: A095956 A014731 A023114 * A202681 A067211 A156337

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 14 20:49 EDT 2024. Contains 374323 sequences. (Running on oeis4.)