A051485 Number of double nodes (exactly two nodes on that level) for all Motzkin paths of length n.

0, 1, 1, 2, 6, 14, 32, 74, 180, 457, 1195, 3177, 8526, 23018, 62441, 170153, 465791, 1280956, 3538618, 9817619, 27348480, 76467497, 214532805, 603732396, 1703728554, 4819990947, 13667248631, 38834528740, 110556072877, 315290709729, 900635841754, 2576615923655, 7381956798465, 21177682172332, 60832837964492

Offset: 0

Author

Wenjin Woan

Keywords

• nonn

Examples

			Of the 9 Motzkin paths of length 4 the following 5 have a total of 6 double nodes:
|1......|
|2../\..|3..__..|2.._...|2..._..|2......|
|2./..\.|2./..\.|3./.\_.|3._/.\.|3./\/\.|
		

Crossrefs

Cf. A001006, A088457.

Column k=2 of A372014.

Extensions

Edited by Michael Somos, Sep 29 2003

a(16)-a(34) from Alois P. Heinz, Apr 13 2024