A280518 Number of increasing sequences of n positive integers with reciprocals adding up to an integer.

1, 0, 1, 7, 78, 2392, 248085, 151428144

Offset: 1

Author

Max Alekseyev, Jan 04 2017

Keywords

• nonn
• hard
• more

Examples

			a(4)=7 enumerates sequences: (1,2,3,6), (2,4,5,20), (2,4,6,12), (2,3,7,42), (2,3,8,24), (2,3,9,18), and (2,3,10,15).
		

Crossrefs

Row sums of A280520.

Cf. A006585 (adding up to 1), A156871 (nondecreasing sequences), A280517 (ordered sequences).