a(n) = 6*a(n-1) + 5*(2^(n-1)-1) for n > 0, a(0) = 0.

Terms

a(0) =0a(1) =0a(2) =5a(3) =45a(4) =305a(5) =1905a(6) =11585a(7) =69825a(8) =419585a(9) =2518785a(10) =15115265a(11) =90696705a(12) =544190465a(13) =3265163265a(14) =19591020545a(15) =117546205185a(16) =705277394945