A007221 Almost-convex polygons of perimeter 2n on square lattice. (Formerly M4304)

6, 216, 3706, 44060, 417486, 3386912, 24554562, 163587572, 1020918342, 6050527496, 34395992698, 188971062108, 1009130882494, 5261414979024

Offset

8,1

References

I. G. Enting, A. J. Guttmann, L. B. Richmond and N. C. Wormald, Enumeration of almost-convex polygons on the square lattice, Random Structures Algorithms 3 (1992), 445-461.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Table of n, a(n) for n=8..21.

Crossrefs

Sequence in context: A370128 A030265 A275567 * A195802 A145249 A154023

Adjacent sequences: A007218 A007219 A007220 * A007222 A007223 A007224

Keyword

nonn

Author

Simon Plouffe

Status

approved