Number of ordinary double points of a family of threefolds.

Terms

a(0) =10a(1) =41a(2) =120a(3) =283a(4) =566a(5) =1029a(6) =1738a(7) =2745a(8) =4150a(9) =6049a(10) =8504a(11) =11661a(12) =15646a(13) =20525a(14) =26496a(15) =33715a(16) =42246a(17) =52345a(18) =64198a(19) =77861a(20) =93654a(21) =111793a(22) =132320a(23) =155625a(24) =181954a(25) =211329a(26) =244216a(27) =280891a(28) =321350a(29) =366141