Scaled Chebyshev U-polynomial evaluated at sqrt(5)/2.

Terms

a(0) =1a(1) =5a(2) =20a(3) =75a(4) =275a(5) =1000a(6) =3625a(7) =13125a(8) =47500a(9) =171875a(10) =621875a(11) =2250000a(12) =8140625a(13) =29453125a(14) =106562500a(15) =385546875a(16) =1394921875a(17) =5046875000a(18) =18259765625a(19) =66064453125a(20) =239023437500a(21) =864794921875