Number of partitions of n*(n-1)/2.

Terms

a(0) =1a(1) =1a(2) =3a(3) =11a(4) =42a(5) =176a(6) =792a(7) =3718a(8) =17977a(9) =89134a(10) =451276a(11) =2323520a(12) =12132164a(13) =64112359a(14) =342325709a(15) =1844349560a(16) =10015581680a(17) =54770336324a(18) =301384802048