Bisection of A002417.

Terms

a(0) =1a(1) =30a(2) =175a(3) =588a(4) =1485a(5) =3146a(6) =5915a(7) =10200a(8) =16473a(9) =25270a(10) =37191a(11) =52900a(12) =73125a(13) =98658a(14) =130355a(15) =169136a(16) =215985a(17) =271950a(18) =338143a(19) =415740a(20) =505981a(21) =610170a(22) =729675a(23) =865928a(24) =1020425a(25) =1194726a(26) =1390455a(27) =1609300a(28) =1853013a(29) =2123410