a(0)=0; a(n) = 6*a(n-1) + 6.

Terms

a(0) =0a(1) =6a(2) =42a(3) =258a(4) =1554a(5) =9330a(6) =55986a(7) =335922a(8) =2015538a(9) =12093234a(10) =72559410a(11) =435356466a(12) =2612138802a(13) =15672832818a(14) =94036996914a(15) =564221981490