A077556 Meandric numbers for an undirected line crossing two perpendicular roads at n points, beginning in the (-,-) quadrant, crossing x axis first and ending in any quadrant.

0, 1, 2, 5, 12, 31, 81, 239

Offset

0,3

Links

Table of n, a(n) for n=0..7.

Crossrefs

Similar to A077551 but line is undirected.

Sequence in context: A000635 A317098 A238427 * A076906 A097893 A093379

Adjacent sequences: A077553 A077554 A077555 * A077557 A077558 A077559

Keyword

nonn,more

Author

N. J. A. Sloane and Jon Wild, Aug 25 2003

Status

approved