id:A136103 - OEIS Search Results

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

+0
2

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 (list; graph; listen)

	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` `and there are 14 signatures dividing 360; but 5 of these also divide 12` `so there are nine new signtures:` `8..24..30..36..60..72..120..180..360`
	CROSSREFS	`Cf. A000108 A000245 A006939 A025487 A136102.` `Adjacent sequences: A136100 A136101 A136102 this_sequence A136104 A136105 A136106` `Sequence in context: A129567 A064469 A057700 this_sequence A053146 A056675 A062857`
	KEYWORD	`easy,nonn`
	AUTHOR	`Alford Arnold (Alford1940(AT)aol.com), Jan 12 2008`

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Last modified October 11 09:12 EDT 2008. Contains 144832 sequences.

AT&T Labs Research