a(n) = 6^n+5^n-1.

Terms

a(0) =1a(1) =10a(2) =60a(3) =340a(4) =1920a(5) =10900a(6) =62280a(7) =358060a(8) =2070240a(9) =12030820a(10) =70231800a(11) =411625180a(12) =2420922960a(13) =14281397140a(14) =84467679720a(15) =500702562700