Generalized Pellian with second term equal to 9.

Terms

a(0) =1a(1) =9a(2) =19a(3) =47a(4) =113a(5) =273a(6) =659a(7) =1591a(8) =3841a(9) =9273a(10) =22387a(11) =54047a(12) =130481a(13) =315009a(14) =760499a(15) =1836007a(16) =4432513a(17) =10701033a(18) =25834579a(19) =62370191a(20) =150574961a(21) =363520113a(22) =877615187a(23) =2118750487a(24) =5115116161a(25) =12348982809a(26) =29813081779a(27) =71975146367