A167243 Number of ways to partition an n X 3 grid into 3 connected equal-area regions.

1, 3, 10, 23, 56, 132, 259, 546, 1095, 2043, 3908, 7379, 13208, 24194, 43819, 76790, 136489, 241311, 416152, 726073, 1261696, 2153026, 3706393, 6364842, 10775173, 18374181

Offset

1,2

Links

Table of n, a(n) for n=1..26.

Example

All solutions for n=4
...1.1.2...1.1.2...1.1.2...1.1.2...1.1.2...1.1.2...1.1.1...1.1.1...1.1.1
...1.2.2...1.2.2...1.1.2...1.1.2...1.3.2...3.1.2...1.2.2...1.2.2...1.2.2
...1.2.3...1.3.2...3.2.2...3.3.2...1.3.2...3.1.2...2.2.3...3.2.2...3.3.2
...3.3.3...3.3.3...3.3.3...3.3.2...3.3.2...3.3.2...3.3.3...3.3.3...3.3.2
------
...1.1.1...1.1.1...1.1.1...1.1.1...1.1.1...1.1.1...1.1.1...1.2.2...1.2.2
...1.2.3...2.2.1...2.2.1...2.2.1...2.1.3...2.1.3...2.3.1...1.2.2...1.2.2
...2.2.3...2.2.3...2.3.3...3.2.2...2.2.3...2.3.3...2.3.3...1.1.3...1.3.3
...2.3.3...3.3.3...2.3.3...3.3.3...2.3.3...2.2.3...2.2.3...3.3.3...1.3.3
------
...1.2.2...1.2.2...1.2.2...1.2.2...1.2.3
...1.2.3...1.1.2...1.1.2...1.3.2...1.2.3
...1.2.3...1.3.2...3.1.2...1.3.2...1.2.3
...1.3.3...3.3.3...3.3.3...1.3.3...1.2.3

Crossrefs

Cf. A167242.

Sequence in context: A294503 A080204 A115982 * A316403 A185828 A134438

Adjacent sequences: A167240 A167241 A167242 * A167244 A167245 A167246

Keyword

nonn

Author

R. H. Hardin, Oct 31 2009

Status

approved