A Pellian-related sequence.

Terms

a(0) =1a(1) =13a(2) =64a(3) =307a(4) =1471a(5) =7048a(6) =33769a(7) =161797a(8) =775216a(9) =3714283a(10) =17796199a(11) =85266712a(12) =408537361a(13) =1957420093a(14) =9378563104a(15) =44935395427a(16) =215298414031