OFFSET
0,2
EXAMPLE
The array begins
1
2
4...6..12
8..24..30..36..60..72..120..180..360
16...
with 1 1 3 9 28 90 ... least prime signatures per row;
hence there are 1 2 5 14 42 132 ... Catalan objects counted.
The staircases can be coded 1 2 12 360 75600 174636000 ...: A006939.
There are 14 signatures dividing 360; but 5 of these also divide 12 so there are nine new signatures: 8..24..30..36..60..72..120..180..360
CROSSREFS
KEYWORD
easy,tabf,nonn
AUTHOR
Alford Arnold, Jan 12 2008
STATUS
approved