A051907 Number of ways to express 1 as the sum of distinct unit fractions such that the sum of the denominators is n.

1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 2, 0, 0, 0, 0, 2, 0, 1, 1, 1, 1, 0, 2, 0, 1, 1, 1, 2, 0, 4, 1, 3, 4, 0, 2, 0, 6, 0, 1, 2, 1, 3, 0, 4, 2, 1, 5, 5, 3, 2, 3, 3, 5, 5, 5, 2, 1, 12, 5, 4, 11, 4, 5, 2, 11, 3, 5

Offset

1,45

Links

Seiichi Manyama, Table of n, a(n) for n = 1..150

Index entries for sequences related to Egyptian fractions

Example

1 = 1/2+1/4+1/9+1/12+1/18 = 1/2+1/5+1/6+1/12+1/20. The sum of the denominators of each of these is 45, these are the only 2 with sum of denominators = 45, so a(45)=2.

Crossrefs

A051882 lists n such that a(n)=0.

Cf. A051908.

Sequence in context: A352550 A348326 A364213 * A178176 A093569 A073091

Adjacent sequences: A051904 A051905 A051906 * A051908 A051909 A051910

Keyword

nonn

Author

Jud McCranie, Dec 16 1999

Extensions

R. L. Graham showed that a(n)>0 for n>77.

Status

approved