a(0)=1, a(1)=7, a(n) = 42*a(n-2) - a(n-1).

Terms

a(0) =1a(1) =7a(2) =35a(3) =259a(4) =1211a(5) =9667a(6) =41195a(7) =364819a(8) =1365371a(9) =13957027a(10) =43388555a(11) =542806579a(12) =1279512731a(13) =21518363587a(14) =32221171115a(15) =871550099539a(16) =481739087291