Hoggatt sequence with parameter d=6.

Terms

a(0) =1a(1) =2a(2) =9a(3) =58a(4) =506a(5) =5462a(6) =70226a(7) =1038578a(8) =17274974a(9) =317292692a(10) =6346909285a(11) =136723993122