A280518 - OEIS

A280518

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

%I #13 Apr 29 2018 02:13:10

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

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

%e 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).

%Y Row sums of A280520.

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

%K nonn,hard,more

%O 1,4

%A _Max Alekseyev_, Jan 04 2017