|
Search: id:A162675
|
|
|
| A162675 |
|
Number of different fixed (possibly) disconnected pentominoes bounded (not necessarily tightly) by an n*n square |
|
+0
5
|
|
| 0, 0, 114, 2910, 26490, 145110, 582540, 1891764, 5263020, 13010580, 29297070, 61162530, 119933814, 223098330, 396734520, 678599880, 1121985720, 1800456264, 2813598090, 4293914310, 6415006290, 9401194110, 13538735364, 19188810300
(list; graph; listen)
|
|
|
OFFSET
|
1,3
|
|
|
COMMENT
|
a(3)=114: there are 114 rotations of the 21 free (possibly) disconnected pentominoes bounded (not necessarily tightly) by an 3*3 square; these include the F, P, T, U, V, W, X and Z (connected) pentominoes and 13 strictly disconnected pentominoes
|
|
FORMULA
|
a(n)=n(n-1)(n-2)(n+1)(5n^4-10n^3-7n^2+12n+6)/24
|
|
CROSSREFS
|
Cf. A162674, A162676, A162677
Sequence in context: A126169 A002952 A108344 this_sequence A112485 A084877 A060309
Adjacent sequences: A162672 A162673 A162674 this_sequence A162676 A162677 A162678
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
David Bevan (dbevan(AT)emtex.com), Jul 27 2009
|
|
|
Search completed in 0.002 seconds
|
