A136103 A Catalan shaped array (A000245) of least prime signatures (A025487) based on staircase Ferrers boards; cf. A136102.

1, 2, 4, 6, 12, 8, 24, 30, 36, 60, 72, 120, 180, 360, 16, 48, 144, 210, 216, 240, 420, 432, 720, 840, 900, 1080, 1260, 1680, 1800, 2160, 2520, 3600, 5040, 5400, 6300, 7560, 10800, 12600, 15120, 25200, 37800, 75600

Offset: 0

Author

Alford Arnold, Jan 12 2008

Keywords

• easy
• tabf
• nonn

Examples

			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

Cf. A000108, A000245, A006939, A025487, A136102.