First trisection of A246584.

Terms

a(0) =2a(1) =26a(2) =160a(3) =784a(4) =3152a(5) =11290a(6) =36556a(7) =110012a(8) =310482a(9) =832224a(10) =2131072a(11) =5249356a(12) =12488368a(13) =28816368a(14) =64676460a(15) =141598304a(16) =303031202a(17) =635197072a(18) =1306210848a(19) =2639071792a(20) =5245173264a(21) =10266881562a(22) =19811351308a(23) =37720810240a(24) =70922550372a(25) =131777935396a(26) =242124952896