|
Search: id:A098487
|
|
|
| A098487 |
|
Lower triangle T(m,k) read by rows, where T(m,k) is the number of ways in which 1<=k<=m positions can be picked in an m X m square array such that all positions are mutually isolated. Two positions (s,t),(u,v) are considered as isolated from each other if min(abs(s-u),abs(t-v))>1. |
|
+0
2
|
|
| 1, 4, 0, 9, 16, 8, 16, 78, 140, 79, 25, 228, 964, 1987, 1974, 36, 520, 3920, 16834, 42368, 62266, 49, 1020, 11860, 85275, 397014, 1220298, 2484382, 64, 1806, 29708, 317471, 2326320, 12033330, 44601420, 177418469, 81, 2968, 65240, 962089, 10087628
(list; table; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
For more information, links, programs see A098485.
|
|
EXAMPLE
|
T(3,3)=a(6)=8 because there are the following 8 ways to pick 3 positions isolated from each other from a 3 X 3 square array:
X0X...X0X...X0X...X00...X00...0X0...00X...00X
000...000...000...00X...000...000...X00...000
X00...0X0...00X...X00...X0X...X0X...00X...X0X
|
|
PROGRAM
|
See link in A098485.
|
|
CROSSREFS
|
A098485 gives selections where all marks are connected, A090642 gives total number of possible selections.
Sequence in context: A100074 A035102 A021248 this_sequence A019127 A019207 A072194
Adjacent sequences: A098484 A098485 A098486 this_sequence A098488 A098489 A098490
|
|
KEYWORD
|
nonn,tabl
|
|
AUTHOR
|
Hugo Pfoertner (hugo(AT)pfoertner.org), Sep 15 2004
|
|
|
Search completed in 0.002 seconds
|
