A339628 - OEIS

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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

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,12

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.

LINKS

Table of n, a(n) for n=0..67.

Index entries for sequences related to compositions

Index entries for sequences related to Egyptian fractions

EXAMPLE

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.

CROSSREFS