The 2-Up sequence: formed from final entries in rows of A058257.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =3a(5) =6a(6) =26a(7) =71a(8) =413a(9) =1456a(10) =10576a(11) =45541a(12) =397023a(13) =2020656a(14) =20551376a(15) =120686411a(16) =1402815833a(17) =9336345856a(18) =122087570176a(19) =908138776681