Meandric numbers for a river (or directed line) crossing two perpendicular roads at n points, beginning in the (-,-) quadrant, crossing x axis first and ending in any quadrant.
A077551
Meandric numbers for a river (or directed line) crossing two perpendicular roads at n points, beginning in the (-,-) quadrant, crossing x axis first and ending in any quadrant.
Terms
- a(0) =0a(1) =1a(2) =3a(3) =5a(4) =16a(5) =31a(6) =105a(7) =218a(8) =770a(9) =1673a(10) =6096a(11) =13672a(12) =51027a(13) =117194a(14) =445787a(15) =1042970a(16) =4028922a(17) =9567393a(18) =37432324a(19) =89984282a(20) =355854272
External references
- oeis: A077551