A129876 Sequence i_n arising in enumeration of arrays of directed blocks (see Quaintance reference for precise definition).

2, 4, 14, 52, 210, 888, 3886, 17448

Offset

1,1

References

Jocelyn Quaintance, Combinatoric Enumeration of Two-Dimensional Proper Arrays, Discrete Math., 307 (2007), 1844-1864.

Links

Table of n, a(n) for n=1..8.

Formula

See Quaintance reference for generating functions that produce A129872-A129886.

Crossrefs

Sequence in context: A003500 A316363 A295760 * A038055 A006385 A322859

Adjacent sequences: A129873 A129874 A129875 * A129877 A129878 A129879

Keyword

nonn,more

Author

N. J. A. Sloane, May 26 2007

Status

approved