Sin(arcsin(n)- 3 arccos(n))^2.

Terms

a(0) =1a(1) =1a(2) =9409a(3) =332929a(4) =3690241a(5) =23049601a(6) =101626561a(7) =354079489a(8) =1040514049a(9) =2687489281a(10) =6272798401a(11) =13493377921a(12) =27138279169a(13) =51591216769a(14) =93489789121a(15) =162571046401a(16) =272735662081a(17) =443365544449a(18) =700932305089