A339628 Number of compositions (ordered partitions) of n into distinct parts such that the sum of reciprocals of parts is an integer.

1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 24, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 24, 120, 0, 0, 0, 0, 24, 144, 144, 120, 0, 0, 0, 24, 240, 720, 0, 0, 0, 120, 720, 240, 1440, 0, 0, 0, 840, 5760, 720, 5160, 744, 240, 720, 1440, 10080, 720, 5760, 5160, 1560, 5760, 2280, 16560, 6000, 7560

Offset: 0

Author

Ilya Gutkovskiy, Dec 10 2020

Keywords

• nonn

Comments

Also the number of ordered ways to express an integer as the sum of distinct unit fractions such that the sum of the denominators is n.

Examples

			a(11) = 6 because we have 2 + 3 + 6 = 2 + 6 + 3 = 3 + 2 + 6 = 3 + 6 + 2 = 6 + 2 + 3 = 6 + 3 + 2 = 11 and 1/2 + 1/3 + 1/6 = 1 is an integer.
		

Links

• Index entries for sequences related to compositions
• Index entries for sequences related to Egyptian fractions

Crossrefs

Cf. A051907, A051908, A058360, A339627, A339629.