Number of unordered pairs of distinct strict integer partitions of n.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =1a(5) =3a(6) =6a(7) =10a(8) =15a(9) =28a(10) =45a(11) =66a(12) =105a(13) =153a(14) =231a(15) =351a(16) =496a(17) =703a(18) =1035a(19) =1431a(20) =2016a(21) =2850a(22) =3916a(23) =5356a(24) =7381a(25) =10011a(26) =13530a(27) =18336a(28) =24531a(29) =32640