|
| |
|
|
A152113
|
|
A001333 with terms repeated.
|
|
3
| |
|
|
1, 1, 3, 3, 7, 7, 17, 17, 41, 41, 99, 99, 239, 239, 577, 577, 1393, 1393, 3363, 3363, 8119, 8119, 19601, 19601, 47321, 47321, 114243, 114243, 275807, 275807, 665857, 665857, 1607521, 1607521, 3880899, 3880899, 9369319, 9369319, 22619537, 22619537, 54608393
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,3
|
|
|
COMMENTS
| Suggested by an email message from Hugo van der Sanden, Mar 23 2009, who says: Consider the partitions of a 2 x n rectangle into connected pieces consisting of unit squares cut along lattice lines. Then a(n) is the number of distinct pieces with rotational symmetry that extend to opposite corners.
|
|
|
EXAMPLE
| Example: the pieces iullustrating a(3) = 3 are:
AAA BB. .CC
AAA .BB CC.
|
|
|
CROSSREFS
| Cf. A001333, A078469, A152124.
Sequence in context: A146450 A174583 A147144 * A146149 A070925 A146687
Adjacent sequences: A152110 A152111 A152112 * A152114 A152115 A152116
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Sep 21 2009
|
| |
|
|
