Generalized Pellian with second term equal to 7.

Terms

a(0) =1a(1) =7a(2) =15a(3) =37a(4) =89a(5) =215a(6) =519a(7) =1253a(8) =3025a(9) =7303a(10) =17631a(11) =42565a(12) =102761a(13) =248087a(14) =598935a(15) =1445957a(16) =3490849a(17) =8427655a(18) =20346159a(19) =49119973a(20) =118586105a(21) =286292183a(22) =691170471a(23) =1668633125a(24) =4028436721a(25) =9725506567