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

Author

N. J. A. Sloane, May 26 2007

Keywords

• nonn
• more

References

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

Formula

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